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VShare and Too Much Memory

How many of you have added memory to your Windows 9x or Windows ME system and found you've been getting more fatal memory errors than ever before? Well, we've got good news for you.

Many of us have kept our old Windows versions for the flexibility of still running our old 16-bit applications and also the new 3D games, and thought if we just had a gigabyte or so of RAM everything would be all right. So what gives with the memory errors?

It turns out that Windows 9X and ME has had a flaw all along in the way they manage RAM over 512MB, and it just never showed up until that 512MB boundary was crossed. Of course, back when Windows 95 came out nobody thought of using it with 512 MB, but now memory prices are down and memory usage is up for just about everything, and adding RAM is usually the best bang for the buck.

The problem is with the 32-bit protected-mode cache driver, called Vcache. This driver needs to reserve some RAM for virtual memory management, but it seems to think that with so much new memory it's all fair game and it gobbles up much of it for the cache, not leaving enough for other functions. This can result in "Out of Memory" errors or even the Blue Screen of Death! Another indirect symptom of this is potential sluggishness of applications caused by delays while data gets constantly swapped on and off the disk because Vcache hasn't left enough RAM for the application.

Fortunately, there is an easy fix. First, back up your system.ini file for safety and then boot to Safe Mode. Go to Start\Run, type in SYSEDIT (in Windows ME you'll need to use MSCONFIG), and add a line under Vcache that limits the size of the cache. The syntax should look like this:

[Vcache]
MaxFileCache=524288

Reboot the machine, and those errors should be a thing of the past.

Until next week, Happy Troubleshooting.