External drives and Vista

I have two WD External Drives.  One is a 250gig and the other is a 2TB.  The problem I am having is when I boot up my computer, all is well.  However, for some reason, they will not be accessible or recognized.  I need to re-boot the computer for them to be recognized again.

I haven’t a clue as to why this is happening.  Any input for this extreme novice would be very appreciated

Paul, I’m a new to this forum site.  For some reason I think this is a windows/vista problem.  I did a recent recommended by windows update to my laptop, which changed several things on my computer, one of which was sidenotes!  Yesterday I did a backup using my WD Passport Essential, and my computer wouldn’t recoginize it.  This was not the first time I backed up to the WD, but was the first time since I updated Vista.  Maybe you’ve done the same thing and just haven’t made the connection.  I keep a log of everything I install on this laptop in case it crashes and I can’t get to the internal information.   sorry not much help.