Why would this happen

[Kris75]

Hey there everyone. I have a wierd issue here with PT 6.4 on a 001. I loaded in two trax of samples to layer the snare. When I did this I was very carefull to have everything lined up, and then consolodated the files to be the proper length for the session. The files worked fine for about 2 days, and then when I loaded up the session today, all of the sampled snare hits were out of time by up to 10ms, in front or behind, no rhyme or reason!!! Luckily I always do a save session as before I begin each session, so I went back to yesterdays session, and wham, the exact same files are perfectly lined up . Why would the exact same files be different in two different sessions?
I hope someone could shed some light on this issue, and is this a known bug in 6.4? Should I use PT 6.4cs... Up until know 6.4 has been a rock solid platform for me.
Thanks in advance.

[Kris75]

I also forgot to mention that all playlists associatied with questionable tracks were also out of sync.

[Kris75]

Shameless bump.