I am working on a project with 8 audio tracks.  I have been recording parts for a couple of days............all of a sudden the timing is off between the tracks.  It is very slight but noticeable.  What should I check?
 
I am using Windows XP.

If you are not using an Audio Interface and ASIO or WDM drivers you will experience this issue. My first set up was a with sound blaster card and it was always "off".  

I am using a Delta 44.  I found the problem I used I was using the LP-65 Multiband compressor on 2 tracks.  When I removed these the problem went away

Yes absolutely that will do it. Best to bypass all efxs bins while tracking, Most will add just a tiny bit of latency you might not notice, but those type are "look ahead" and can add a LOT of latency. SO for good timing you always bypass all bins 
ctrl/shf/y

The LP-64 has had longstanding latency issues. Most users gave up trying to use it on tracks, although it's no problem on the master bus with adequate buffer sizes. If you need multiband compression on individual tracks, I'd suggest using the Sonitus Multiband instead. Only use the LP-64 on the master and only after you're done tracking.