yeah, laptops sometimes dont run so hot on this game.
go to
http://v4.windowsupdate.microsoft.com/en/default.asp
make sure that youre operating system, graphics card drivers, and such are all updated to the most recent specs. this will most likely solve the problem.
(spoiler) the puzzle cannal is at the vivec temple, go there via the boats, and come off the ramp. turn right off the ramp and you'll come to a huge pyramid that is behind the normal temple. go up to the third level and jump into the canal at that ring (not all the way up to the top where the door is). you will be able to go into one of the drains there. the middle of the cannal will have a passage leading between the two waterways and in there will be the entrance to vivec's puzzle canal. let me know if you can't figure out the puzzle... and just a hint, dont attack anything in there. Oh, and silver longswords are in the chest by the shrine... you'll know what i mean.