SQL Server 2008 Mirroring Pauses without warning
If you query the sys.database_mirroring catalog view you should find out the status of database mirroring from the mirroring_state field.  Try this:

select 
    DB_NAME(database_id),
    mirroring_state
from sys.database_mirroring


When it "pauses", what does the mirroring_state show?  Here is a legend:

0 = Suspended

1 = Disconnected from the other partner

2 = Synchronizing 

3 = Pending Failover

4 = Synchronized

5 = The partners are not synchronized. Failover is not possible now.

6 = The partners are synchronized. Failover is potentially possible. For information about the requirements for failover see, Synchronous Database Mirroring (High-Safety Mode). 

NULL = Database is inaccessible or is not mirrored.