Just a general observation...
4.2 client & a 3.7 server is not listed in the general "supported
environments" matrix.
An environment as a whole is only supported if the clients are
        1 level back
        same level
        1 level forward
of the tsm server to which they back up.

Granted this doesn't help your current situation but needs to be pointed
out.

Also your server is out of support (as of Oct 31st I believe)
        this doesn't help your situation either...

In your sched.log is there a specific file that it is failing on  ? ? ?
might try running a backup of just that file to see if that will run...
if that blows also, might try using that file to verify it.

but I'd look into bringing your tsm server up to current levels of software

(sorry, I'm sounding like IBM)

Dwight