DB_Link

Have any one experience the following problem with a db_link?
My OS is HP-UX 11.0, database is Oracle 9.2.0.7

Problem:
I have establish a db_link to push information to a remote server
via two Procedures. Every thursday night, I shutdown my database to do a coldbackup. When the database restarts, the db_link become inactive. When I check on friday morning it showed this message:

link PM_online error: Ora-12154: TNS:could not resolve service name.

I checked to insure all oracle processes were up, and they were.
I tried testing the link by selecting * from dual@PM_line. Got the oracle error ora-12154.

How can I re-establish my link without bouncing the database?

dont bounce it in the first place seems to be the best solution

TNS-12154 means the service name you are using in the db link cant be found in the tnsnames.ora file

I checked my tnsnames.ora file, the service name that I am using for the db_link is there and it is in the correct format.
Why is it not being detected after I restarting the database from a cold backup?
Is there a simple fix to this problem without bouncing the database?