recently my Webmethods JDBC pool often failed to connect oracle db

Hi, recently my Webmethods JDBC pool often failed to connect oracle db, in this case , I have to restart IS.After restart, the connection is restored. Farther more, sometimes I have
to restart the server (HP DL380), or else IS can’t be
restarted successfully, it’s pending at
2006-12-06 20:06:14 PST [ISS.0025.0017C] Repository Manager started , and it can’t go to the next step
JDBC Connection manager started.This way, the connection will keep OK for about 10 hours, and then I get the same errors as below again.Your help is appreciated.

Crane