I can't remember where I found this one, and I'd be interested in learning if there are any other helpful start-up parameters. Yes, there are more start-up parameters. X switch you've been using excludes all of the adapter area from the memory Windows scans when it seeks unused space. Apparently one or more adapter cards on your system use memory in the range that Windows fails to perceive.
X switch every time.
This technique isn't restricted to Windows 3.x, either. Multiple DOS Sessions Submit a tip or question.