This error is caused by an application trying to divide by zero. If you receive this error and don’t know which application caused it, you might try examining the memory dump.
The IRQL_NOT_LESS_OR_EQUAL error is caused by a buggy device driver or an actual hardware conflict. If you’ve recently added new hardware to your system, try removing it and see if the error goes away. Likewise, if you’ve recently loaded a new device driver, you might try using ERD Commander Professional Edition, by Winternals Software, to temporarily disable the new driver and see if the problem goes away.
An incorrectly configured device driver usually causes this type of error. As I’ll explain later, you can use another section of the blue screen to figure out which driver is causing the problem.
Such an error indicates a catastrophic failure in the system’s registry. However, this error can sometimes be caused by failure to read the registry from the hard disk rather than because the registry itself is corrupt. Most of the time though, if you get this error, you’ll have to restore from backup.
Just as the name implies, this error indicates that Windows NT is having trouble reading from the hard disk. This error can be caused by a faulty device driver or a bad small computer systems interface (SCSI) terminator. If you’ve checked for these problems, but are still receiving the error, check to make sure that a virus hasn’t destroyed your boot sector.
This error message is almost always caused by your computer’s memory. If you receive this error, check to make sure that all of your single inline memory modules (SIMMs) are the same type and speed. You should also check to make sure that your computer’s Complementary Metal Oxide Semiconductor (CMOS) is set for the correct amount of RAM. If all of these suggestions check out, try replacing the memory in the computer.
This is, perhaps, the most obscure error message. In most cases, if you receive this error, it’s related to the most recent change you’ve made on your system. Try undoing the change to get rid of the error.
An NTFS_FILE_SYSTEM error indicates hard disk corruption. If your system is bootable, run CHKDSK /F on all of your partitions immediately. If your system isn’t bootable, try installing a new copy of Windows NT in a different directory. You can use that copy to run the CHKDSK program. When you’re done with the second copy, you can edit your BOOT.INI file to make your computer start your original copy of Windows NT.
This error indicates that Windows NT wasn’t able to read a page of kernel data from the page file. Bad memory, a bad processor, incorrectly terminated SCSI devices, or a corrupt PAGEFILE.SYS file may cause this situation. The first step in correcting such an error is to recreate the PAGEFILE.SYS file and see if you can bring your system back online.
This is a generic error message in which the hardware abstraction layer can’t report on the true cause of the error. In such a situation, Microsoft recommends calling the hardware vendor. This error can sometimes be caused by mixing parity and non-parity SIMMs, or by bad SIMMs.
Web Server Error Messages:
400 Bad File Request
Usually means the syntax used in the URL is incorrect (e.g., uppercase letter should be lowercase letter; wrong punctuation marks).
Server is looking for some encryption key from the client and is not getting it. Also, wrong password may have been entered. Try it again, paying close attention to case sensitivity.
403 Forbidden/Access Denied
Similar to 401; special permission needed to access the site — a password and/or username if it is a registration issue. Other times you may not have the proper permissions set up on the server or the site’s administrator just doesn’t want you to be able to access the site.
404 File Not Found
Server cannot find the file you requested. File has either been moved or deleted, or you entered the wrong URL or document name. Look at the URL. If a word looks misspelled, then correct it and try it again. If that doesn’t work backtrack by deleting information between each backslash, until you come to a page on that site that isn’t a 404. From there you may be able to find the page you’re looking for.
408 Request Timeout
Client stopped the request before the server finished retrieving it. A user will either hit the stop button, close the browser, or click on a link before the page loads. Usually occurs when servers are slow or file sizes are large.
500 Internal Error
Couldn’t retrieve the HTML document because of server-configuration problems. Contact site administrator.
501 Not Implemented
Web server doesn’t support a requested feature.
502 Service Temporarily Overloaded
Server congestion; too many connections; high traffic. Keep trying until the page loads.
503 Service Unavailable
Server busy, site may have moved ,or you lost your dial-up Internet connection.
Connection Refused by Host Either you do not have permission to access the site or your password is incorrect.
File Contains No Data
Page is there but is not showing anything. Error occurs in the document. Attributed to bad table formatting, or stripped header information.
Bad File Request
Browser may not support the form or other coding you’re trying to access.
Failed DNS Lookup
The Domain Name Server can’t translate your domain request into a valid Internet address. Server may be busy or down, or incorrect URL was entered.
Host server down. Hit reload or go to the site later.
Unable to Locate Host
Host server is down, Internet connection is lost, or URL typed incorrectly.
Network Connection Refused by the Server
The Web server is busy.