Problems since RAM upgrade

I've recently upgraded my MBP 2.4 Ghz to 4GB RAM. Since i've done it i've had a few strange problems:
Dock Hiding no longer works
Can't drag & drop from Finder
Menu Options don't stay open

i've tried repairing permissions, i've reinstalled OSX 10.5.0 and installed the upgrades and I've still got the problems as above.
Does anyone know how I can sort this out? it's not a major problem but it is pretty irritating!
thanks
Mike

It would be strange for those specific issues to be memory related but I would pose a couple questions to you.

1) Have you tried reverting to the factory RAM configuration and tested to see if the issues remain?

2) Did you use a matched pair of RAM?

3) What was the exact RAM you used and did you research that it was fully compatible with your model of Mac?

4) Can your model of Macbook Pro support 4gigs of Ram? Only the most recent can.