Lock-up issues

OK, I'm running the most current version of Parallels 6 on a MBP i7 with 4GB of memory using OSX 10.6.4. I allocate 1GB of memory to Parallels, and it's running Windows Vista (not going to waste money upgrading to Windows 7, since I only have Windows to test Powerpoint presentations and websites, and to run one GPS program from a company that refuses to support the Mac). I run Parallels off of an external hard drive connected to my MBP via USB 2.0. I do this because I once had a crash with Parallels that corrupted my hard drive. Lucky for me, I back up everything on Time Machine, but I will never trust Parallels again on my main hard drive.

Anyways, sometimes, but not always, I will fire up Parallels and it locks my MBP. It's temporary, maybe lasting 5 minutes. I know it's not crashed, because the mouse works. Eventually, my MBP gets really slow, reacting to mouse clicks a minute later. This goes not for another few minutes.

This happens while Parallels and Windows is going through the start up phase (I can't remember what the screen says, but there's a green bar showing progress). Once it hits the Windows login screen, everything clears up.

Again, this doesn't happen every time. It never happens during a restart, after getting Windows updates (a frequent requirement...not to pontificate, but wow, makes me love OSX even more). I can't find a constant that would allow me to track down the issue.

Am I doing something wrong? Is there a preference that needs to be adjusted? Or is this just a random issue that everyone experiences?

I know, this might be too ephemeral to get a solid answer, but I'm hoping that there's a simple fix.

 

The latest version of Parallels desktop is 6.0.11826.

Are you using Time Machine or virus / disk protection software on the Mac?

Do you use snapshots in your VM, or the Pause/Suspend feature?

Is your virtual machine set to automatically compress virtual disks?

You could try disabling or not using all the above and see if there's any improvement.