Was this working fine till now?
I have had similar issues when I've used a WebService in my Web apps....
The following is not a favorite style of correction, mostly because it fails
the first criteria of tech support, find the problem before you fix it.
Anyway, if you'ved checked and there are no locks, blocks or similar and
you're sure that this is not a Network issue, then you wish to try what I
often do which is if everyone is out of the web to close the Asp_Net.exe, it
should automatically re-open and for whatever reason refresh and speedup.
I'm not sure if this is a .Net issue or SQL issue, but it closes all the
open session in the SQL database, which works equally well but takes longer