Intelligent trojan?

I hope you can help!

I appear to have attract some kind of malware that's hijacking my browser.

Normally it's fun to hunt these things down. But this time, it's problematic...

Pandasoftware.com wouldn't do an active scan, reporting errors.

Hijackthis wouldn't save a log, reporting errors.

I rather think that the malware itself is foiling me on both these counts...

Avast scanned OK, but reported no viruses found.

I'm not sure what I can do next! Help please!