Windows

Exception & fatal exception errors are often caused by memory management problems (welcome to Windows 98!). You might also have damaged physical memory. I don't know what your memory configuration is, but assuming you are using more that one memory stick, run your system on just one. If no problems, replace that one with another. If you can make your problems return, you should be able to pin down the culprit that way.

Other things to consider:
Are your memory sticks all the same speed?
Assuming you use IE, reduce your Temporary Internet file folder's hard drive setting to 5mb or less (Tools/Internet Options/Settings).

Good luck.

There is a known bug in the W9X code that can cause problems with more than 511MB of RAM installed.

This bug is VERY configuration dependant.
The supported fix from Microsoft is to reduce the amount of installed RAM, or add a line to the startup files to limit the amount of RAM that Windows uses.

I stop at either 256MB or 384MB for all of my 9X boxes.

I recently read about another bug in the 9X code where it has problems with CPUs faster than 2GHz.
Since W98 is in the extended support phase, Microsoft has no plans to fix this bug.

The only other thing that comes to mind, is to make sure that your motherboard chip-set and video card drivers are up to date.
Many video cards have problems with both IE 6 and DirectX 9

Your best 'fix' may be to upgrade to Windows 2000 or XP.

Chas