I've had a long standing problem with vmware fusion 3 whereby if I left my Windows XP 32-bit virtual machine to idle, Vmware fusion would soon start to use 80-100% cpu even though the virtual machine was using virtually no resources accoring to windows task manager. As soon as I started interacting with the virtual machine again the Mac's cpu usage would go back down to normal. I read that the Hardware Abstraction Layet (HAL) was a candidate source of this kind of problem so I modifed it a few times but the problem did not get resolved.
I decided to do a fresh installation of Windows. I originally kept all the default settings chosen by quick install but then increased the RAM allocation to 2GB. I suspected the antivirus as a potential cause of the troubles so before installing all my applications I played around with different antivirus and firewall software combinations.
I am running VMware Fusion 3.1.3 under Mac OS 10.7 with Windows XP SP3 as the guest OS.
No Firewall + No Antivirus = No Issues
Windows Firewall + No Antivirus = No Issues
Windows Firewall + Microsoft Security Essentials = Encountered high idle cpu problem described earlier
ESET Smart Security 4 (this is what I used in my old, abandoned virtual machine) = Encountered high idle cpu problem described earlier
Windows Firewall + Avira Antivir Personal = No Issues
After finding a firewall and antivirus combination that seemed to work well, I installed all my applications, enabled forlder sharing, and have been using the virtual machine for several days with no problems emerging (vmware cpu usage generally below 4% when idle) so based on my experience, certain antivirus packages can cause problems with idle cpu usage.
I'd welcome any comments on this. Is this a phenomenon that others experience?
What combination of Fusion/Windows/Firewall/Antivirus have you had problems with?
What combination works well for you?