The message refers to the Spool32.exe file, a program Windows uses to process your printing without tying up your computer.

When you order a print job, Spool32 stores it on your hard drive and from there sends it on to the printer. That means that your main processing chip does not have to deal with the printing work and can go on with its other chores.

The error message is saying that something is interfering with this scheme.
The next time you get the message, look carefully at the first line in the error box, specifically at the line beginning, "SPOOL32 caused a . . .," because there are several Spool32 error triggers.

If the message indicates that the Spool error came about in your printer - if your printer's name or its abbreviation are listed in the error message - reinstall your printer driver. Better yet, go to the Web site maintained by the printer's manufacturer and download an updated driver.

Does the error finger Spool32.exe itself? Then the Spool32.exe file has been clobbered and you need to get a new one from your Windows CD.

You might also want to clear out some space on your hard drive and then defragment the drive. You might be getting the error because the Spool utility is having a hard time finding enough space on the drive for the spool file - especially if you are trying to print big files or a massive amount of information off the Internet.

It is also a good bet to clean out the C:\Windows\Temp folder. If it gets too full it can cause the error message.
Finally, also check your Spool directory. Close any pending print jobs, then open Windows Explorer. Go to Windows/Spool/Printers. Delete any files you see in the Printers folder.