bridge - can't delete files in some folders

I just installed CS3 on my new PC. My problem is that in SOME (but not all) folders when I hit delete to get rid of some files it just totally ignores the command - it's not rejecting it - i've tried ALT+ delete and even the dustin icon at the top right hand side. NOTHING - it's as if i haven't pressed anything.

then i've opened other folders (on the same drive) and the delete works like a dream. around half the folders on my drive have 'deletable' files and half are completely stuck. I copied one folder onto a different drive and from there i am able to deletes files from it.

any ideas what is going on????????????????

thanks

desperate in London!