In other threads, I've mentioned a similar problem that I've had. Since I use Mcafee instead of Kaspersky, I'm not sure that Kaspersky is the source of the issue. I am running Parallels 6 and Win7. My first experience was with the just previous build of v6. The guest OS crashed hard during the installation of Parallels Tools. It blue screened, and also failed to start up. In this case, the native Win7 start-repair functions seemed to work. However, I could not get Tools consistent with that version to install; the process consistently died just after getting to the time synchronization functions and would then back out.
I paid for a tech support call, and after a couple of hours, uninstalling and reinstalling, disabling and then uninstalling Mcafee, regedits galore, and downloads of the Tools files from obscure locations, the support guy simply had me fall back to the previous version. Now, when the latest build came out, I went ahead and did the install, got a blue screen along the way, but the machine came back up OK and Tools installed fine. I thought things were cool for a few days. The latest build appeared to work very well under OS 10.6.5, with Aero now functional, and an issue I'd had with Shared Folders also suddenly cleaned up.
Then, I began to get obscure problems with various applications and system functions. For example, the Task Manager's performance functions would report invalid DLLs. Acrobat Distiller could not find its ICC profiles. A print utility called Quad Tone RIP began to fail. I ran a chkdsk function, and it reported problems with index $I30. Chkdsk ran, but file corruption reports continued. I tried uninstalling and reinstalling Acrobat about 5 times (really) and no matter how I executed the reinstall it would always report not finding ICC profiles. To some extent, this is a known problem if you don't install Acrobat as Admin, but I was aware of this and did the accepted procedure.
Finally, I gave up and went back to an HDD image of my Win7 machine that I'd saved last September. In redoing my VM with this starting point, I got a working system without any problems installing the latest version of Tools with the latest build of v6. Of course, this older starting point was behind times in Windows updates. As it went through the process of bringing itself up to date, it crashed hard during the install of the most recent 8 or so Win7 security updates. This crash killed the guest OS and the host OS as well (Mac OS X 10.6.5 on a dual core iMac). After the host OS restarted, the guest OS was completely destroyed, and the internal boot repair functions could not recover it.
Now, I'm lucky enough to have decent backups and at least one version of the VM that I can recover all my Documents from. Consistent with others in this thread, I have been running with the hypervisor enabled and 2 CPUs allocated to the VM. I haven't tried starting over with my September back up and hypervisor disabled, but based on what I've read here, I'm going to try that today.
My expectation, given my own experience and what I've read here, is that there is some incompatibility between one of the recent Win7 security updates and the last two builds of v6, perhaps if and only if hypervisor is enabled. If starting over with my September build and hypervisor disabled seems to work (or not) I'll report this here.