Problem with Vuescan and Lide 20

Hi ppl.
After getting frustrated with the crappy scanning software provided by
canon, I decided to try vuescan. The number of options impress me and
I'd love to buy it.
However there is a problem with it and my Lide 20. Sometimes
everything works fine. But other times, whether beginning a preview or
a scan, the scanner makes an awful sound like the scan head is trying
to move but is stuck. A few minutes ago I clean installed vuescan to
see if that would help. At first it seemed to, then that horrible
sound again. I lifted the lid and the scanhead, which should have been
returning to the top of the page, wasn't moving. It's as if something
- software or driver - is fighting against what vuescan is doing. It
usually occurs when a scan or preview is initiated. Sometimes clicking
the abort button stops it. Other times I have to disconnect the
scanner from the usb port.

I own other scanning related software, all which seem to work fine.
Finereader for instance works great using its built in interface. At
the moment only vuescan is installed though.

Has anyone else had this problem? If not, then in the next couple of
weeks I'll do a clean install of XP to see if that fixes it.

regards,
Dave