This just happened last night. I have a 6 year old Compaq Presario (one of the worst computers anyone can get), 400mHz K6 processor, 64 MB RAM, Windows 98 First Edition.

I was chatting and browsing like usual, and one or more programs started making my computer go all grindy and unresponsive, which happens alot. I tried closing the programs and restarting, but the computer froze, which also happens alot. Then I switched the computer off in the back, waited, and turned it back on... which also also happens alot.

But this time, after the red-on-black Compaq screen came up, instead of going to the Windows splash screen, it immediately had a message that said "Program caused a divide overflow error. Contact program vendor if problem persists." (or something very similar to that). I hadn't ever seen that before, even after having switch it on and off like that probably a few hundred times.

I Ctrl+Alt+Del'ed to restart it, and it did the exact same thing. I put in my DOS boot disk and restarted, and it did the exact same thing. I even put in QuickRestore (the HD formatter), and it did the exact same thing. Then I tried all the other F- keys, and the only one that worked was F10, which seems to bring up the BIOS. That worked. But I haven't dealt with the BIOS before so I wasn't sure what problems to check.

I think it was the POST check that I changed to "full" that made it count from 0 to 65536 when I restarted, and it said something about the memory size being incorrect, I think. I messed around with more options for awhile but it never got rid of the "divide overflow error" on attempted startups.
I'm pretty much lost now. Someone suggested I remove the RAM stick and clean it a little, though I'm not sure that'd work. There's a chance that getting a new RAM stick in there would fix the problem, but I don't want to waste money on a wild guess like that. Has anyone dealt with this sort of problem before

Pulling and cleaning the contact on a ram chip is simple and free.
If it has multiple chips, remove one or the other and see if the problem changes.

64 megs... you need more ram

There is an issue with K6 and processors over 350 that might be part of the problem. It was supposed to only be a problem for 95 and not 98 but some PC's that were upgraded also had the problem.

If you do end up formatting and doing a fresh install get a copy of 98se... The second edition fixed many many problems.

Also get a copy od 98 lite and remove Internet Explorer and replace it with Firefox or Opera or some other....