FixedDocument printing issue (resolved by TeamViewer???)

FixedDocument printing issue (resolved by TeamViewer???)

So, I have a WPF (.NET 4, MVVM, if it's important) app, that fetches some
data from database, creates FixedDocument and then does one of these two
things:
'print without preview': sends it to print without a preview;
or 'print with preview': displays it in DocumentViewer control and, on
clicking 'Print', sends it to print;
On vast majority of workstations and printers this works just fine.
However, there are some, that sometimes experience problems: printing
doesn't work.
Reported symptoms:
when executing 'printing without preview', all documents just stack up in
printing queue and do not print;
when executing 'printing with preview', preview's loading bar (which waits
for data get and FixedDocument creation) stops and preview doesn't show;
these problems are not consistent - they just come and go;
the moment, when somebody connects to that workstation via TeamViewer,
everything continues - all items in Printing Queue print out, loading bars
continue, previews are shown etc. I know... ;
I have never witnessed this problem myself - on my workstations everything
works fine, the only way, to get to the problematic workstations is
through TeamViewer;
usually, workstation (or sometimes printer) restart fixes the issue - next
printjob works fine;



Are there any theoretical clues?
How can this be, that TeamViewer unfreezes my processes?
One possibility could be: TeamViewer, when connected, opens some ports,
that are necessary to get the data, but subj problem doesn't repeat
constantly (which it would, if there were closed ports) and there are no
DataGet timeouts (which there would be, if it was a network issue)...