VPN-RDP printjob fails after first page

Environment:
WS 2008 R2 Terminalserver (we have 3 of them).
Client VPNs into Company Network and establishes a RDP-connection to one of the TS (load balancing).
Printer is a HP LaserJet 1200 and it's plugged in via USB at the client-machine (Win 7 32bit).
We installed the PCL 5 driver at the client. On the server, RDP Easy Print is used.
The printer has already been reinstalled.

When the client tries to print a list out of an application for value-added-taxes, it spools the printjob at the server. The printjob vanishes really quick at the server-print-queue. At the client, the print-job loads very slowly. It loads 1.44 MB out of about 12 MB and rests. After a (long) while, the job loaded 3 MB and prints the first page (out of about 10). After that, the job fails at the client.

Printing locally and out of other applications on the terminalserver works perfectly. But I can't say if there are other problems on the terminalserver with large documents because the above mentioned application is the only one that produces such big documents (anything other has maximal 2 sites).

I don't have any idea to solve this. I hope anyone can give me a few tips to solve this problem or find the problem.

Edit: If nobody has an idea, it would eventually help to know what you're doing to troubleshoot printing (over rdp). I'm open to any proposal.