Is there is solution to a runtime error other than a reformat?

Try reinstalling the program which is causing the issue.

If it is not a program you or the user has installed and feels is valid, try a malware or spyware scan.

I do not think you need to reformat, rather fix the program which is terminating. From your error you provided, I can not tell which program that would be.

c:/prog is that correct? prog.exe is flagged as a potential virus. Go to Start > Run... and type in msconfig click on Startup tab and see if there is any reference to a prog.exe. Check all the path's listed. If you find one that lists prog.exe uncheck and restart the computer. Run a full scan with a good antispyware/ antivirus.

If the above solutions don't work, you can try the following:

Put your Windows install disk in the disk drive, and go to Start->Run, and type "sfc /scannow", without quotes.  This will scan your system files and repair any that are damaged, but you may have to run Windows Update because this may revert some system files to non-updated versions.

Cheers,
Nick

All 3 solutions are a great place to go. I will let you know how it went tomorrow after I meet up with customer.

Use safe mode to clean malware.

here a troubleshooting guide :  http://www.registryrepairsolutions.com/fix-runtime-errors.html

It could be bad ram chips - verifiable using memtest86