If I try to start and leave open more than 2x command prompt (DOS shell), I always get the error message: "not enough memory for this operation". Many virtual memory values have been tried out. Current values: min=512 max=512

First change your virtual memory to let "Windows Manage it". There is no need for you to "optimize" it. That only causes problems. Run System Tools - Disk Cleanup program to clear out junk files. Then Defrag and make sure you have plenty of free space on the disk drive. Then try again. If you still have problems, are you sure you only have 512MB of memory installed. Having more then 640MB will cause the error you are getting. Try working through ME Fixes Fixes for things that could help.

I disagree - Managing your own virtual memory has advantages. First, you can limit Windows from eating all of your hard disk space if you decide to use a program that requires a lot of memory (or maybe from a memory leak). Second, the Swap file will not become fragmented. That only happens when Windows manages it, because it is constantly being resized. A fragmented swap file can make your computer slower if you don't have much RAM, or if the ConservativeSwapFileUsage=1 line is not added to the System.ini file (under the 386Enhanced section). In regards to the original problem, it may be that the DOS command shell cannot access enough memory, not that it the memory isn't truly free. -Burbble