Vista - Mouse goes nuts - but only when drag/selecting

Using a Logitech 300 wireless dektop with the "Cordless click" mouse and
RC1

Driver is installed and everything works fine including enhanced functions
like sideways wheel clicking.

But if I try to select text, the mouse seems to go hypersensitive and will
go between selecting the last x characters and selecting the last xx lines.
Even holding it steady has it bouncing the selected text between a little
and alot - presumably because the sensitivity is beyond the mouse
resolution.

The only way for me to select what I want is to use the arrow keys.

Any ideas on this one?

Thanks

Bill