Svchost hogging CPU

Hi there,
Will you please help with a maddening problem?
I run Vista home premium on a Compaq 6820S after a reinstall following a hd crash, using an iso from getintopcs.com (dodgy?)
Drivers were installed from HP.
Everything works, but performance is terribly sluggish due to almost 100% cpu usage by svchost.
Process Explorer shows the svchost running taskeng.exe to be the culprit. There are actually 2 instances of taskeng, one seemingly legit but access denied to the other.
Numerous malware scans came up clean.
Starting in safe mode shows normal CPU usage.
Prior to the HD crash there were no problems.
I'll attach a Hijackthis logfile, fwiw.
I'd appreciate any help tremendously.
Grateful thanks,
Martin.