Please help - Time Machine and Finder App acting strange...

Hi - wonder if someone can give me some guidance...

My Macbook Pro (10.5.2) is acting strange in two respects. Problem has started about 2 days ago.

1st - Finder App: on startup, if I try to click on the finder icon on the dock I get an error 'cannot find the application'. However if I click on the 'downloads' icon and then click 'finder' on the downloads list, the Finder finally opens and is accessible from the dock from there on. One more note: from startup until I go to downloads the bar at the top of my mac (with the clock, etc) is not present. It comes back though after I click downloads.

2nd - Time Machine: I noticed my time machine icon was not loading on the top bar next to the time. So I went to my preferences and Time Machine looks like it is off. I did not turn it off. However I can't turn it on as it is locked. On clicking the lock I am not asked for a password, nothin. So I cant turn on Time Machine.

I have tried repairing permissions on my mac hd in the disk utility. This did nothing. My Time Machine was running up to about 2 days ago - is there a way to rollback the entire system to then maybe? Or should I just try and repair these two individual issues.

Thanks for any help you can offer.

Follow up

Hi - one more thing: I just ran Onyx Verify Permissions and this is what was returned:

Started verify/repair permissions on disk disk0s2 Macintosh HD
Group differs on "private/var/root/Library/Preferences/.GlobalPreferences.plist", should be 0, group is 90
ACL found but not expected on "Library"
ACL found but not expected on "Applications/Time Machine.app"

Finished verify/repair permissions on disk disk0s2 Macintosh HD

Not sure how to interpret this!