Installation problems, can't install packages

hi,
I just started a fresh install - white screen appearing when package installation step is carried out (also when 0 packages are selected).
Did you get this as well and how did you solve this?
(using 2.5, win xp)

Thanks in advance.

error message:
Call to a member function fetchRow() on a non-object in C:\Inetpub\wwwroot\bitweaver\users\BitPermUser.php on line 832