MIKEDFUNK  I used Parallels at work to simply debug web apps in Internet Explorer. I have a Mac Pro 2 x 2.66 Ghz with 3 GB ram with the latest leopard install. I had MAJOR problems with Parallels 4. When I left it running beyond when my computer went to sleep I would get an unresponsive machine after a while and would restart. When I restarted my user account would not show up in the login options.

The first time this happened I did a time machine restore, losing some work in the process and taking valuable time out of my day. The second time I realized there was a problem with time machine and it hadn't backed up in ages. Turns out my user folder was still there but it had been "un-blessed" and was not showing up in the list of users. I couldn't even log in as a guest user, the option was missing from the login screen. I eventually found a way to create a new user with a command in single user mode I found on the web and transferred all my files to the new user account.

Before you attribute the problem to something else understand I am careful to keep up with maintenance and run a lean, minimal system. I run Onyx regularly, zap pram regularly. The only thing I run in my menubar is SoundSource. I update Leopard every time an update is released. I had Windows XP installed with all the updates available and ran that the same way.

I have since ditched Parallels in favor of Virtual Box. It runs well on my machine and has almost all of the features of Parallels but for FREE. Coherence, shared networking, saved machine state, file sharing between machines, even cmd-c and cmd-v work. Parallels not only jacked my machine twice but it was also slow and buggy. Sometimes the save state file would get corrupted. Early on in v3 I tried to use parallels with the boot camp partition - that was a nightmare too. It didn't save the machine state and often wouldn't even start up. The coherence mode always had choppy dragging of windows and still does. I gave Parallels a fair shot with versions 2, 3, and 4 and finally got sick and tired of the slow startup even with a saved state, spinning beach ball, and eventually it destabilizing my entire system. I would not use Parallels now even if it was free.  
(Version 4.0.3844)

MIKEDFUNK  I am not able to save my password for an FTP mount with v2.0.1 on Mac OS 10.5.4. When I check "Save Password in Keychain" and click OK to mount it says "The application ftpfs_askpass quit unexpectedly" and then slides down a notice - "Could not mount filesystem: Mount has timed out." Would love to be able to save passwords and load them from the keychain.  
(Version 2.0.1)