I have the same problem on a dell laptop Latitude D505 and Ubuntu Lucid 10.04 32-bit
$ uname -a
Linux clausen-laptop 2.6.32-16-generic #25-Ubuntu SMP Tue Mar 9 16:33:52 UTC 2010 i686 GNU/Linux
I am not certain, but I think that kernel 2.6.32-15 did NOT have this problem.
For me it only happens on login. By software installation and so on I only enter passphrase once.
I have the same problem on a dell laptop Latitude D505 and Ubuntu Lucid 10.04 32-bit
$ uname -a
Linux clausen-laptop 2.6.32-16-generic #25-Ubuntu SMP Tue Mar 9 16:33:52 UTC 2010 i686 GNU/Linux
I am not certain, but I think that kernel 2.6.32-15 did NOT have this problem.
For me it only happens on login. By software installation and so on I only enter passphrase once.