XA Pool messages...what are they for?

I am getting tons of messages as follows:
[16:28:47,321,XAPoolDataSource] Creating XA Pool
Can anyone tell me exactly what that means and whehter its normal to see your server.log full of those messages??
The reason I ask is we are hosting an application for someone that has suddenly started to slow down. They have added more people to their staff but I don't think the issue is the number of users.
We are running on solaris 9 with apache 2.0.40 and JBoss-2.4.6_Tomcat-4.0.3.
Sitting behind that is a Postgresql-7.2.1 database.
After running "sar" I noticed that there have been several times throughout the day that the processor was at 0% idle. There seems to be a large number of httpd instances...(37 sounds high to me but I suppose it could take alot more) and 25 postmaster instances.
During the many of the times where jboss is hogging the cpu, I am getting some exeptions in the log file such as:
[16:34:29,524,XAPoolDataSource] Creating XA Pool
[16:34:29,539,STDERR] Attempt to find failed.
[16:34:29,542,STDERR] Finder exception: javax.ejb.ObjectNotFoundException: invalid primary key supplied
Which to me seems like some sort of invalid query, but I could be mistaken here as I didn't write this app, but have now been told I need to support it...you know how it goes...
Any info would be great.
Thanks