Virtual PC 2004 SP1 is constantly hanging inside the virtual PCs

I am using Windows XP Professional SP1 with all critical updates through
1/4/2004 (can't apply SP2 per corporate policy) on an IBM Thinkpad T41 (1.7
GHz & 2 GB RAM). Virtual PC 2004 base level worked great. I applied SP1 &
all virtual machines are slow & hang. I updated all additions & followed the
performance enhancment page but no change. I removed Virtual PC 2004 SP1,
installed Virtual PC 2004 base level, & the speed/performance issue was no
longer an issue but all networking was broken. All adapter types in the
virtual PCs cannot get an IP address when set to DHCP. Creating new vitual
machines, remocing & reinstalling the additions, & using my existing hard
disks still doesn't change anything. What is going on here?

 

I have found the solution. I installed Virtual PC 2004 SP1 on a different
machine, mapped a drive to use my existing virtual hard disks with the
problem. Created new virtual machines to use the existing hard disks, &
updated/installed the SP1 virtual machine additions.

After that all Virtual Machines & Disks worked fine on my base level Virtual
PC 2004 machine.