c# how to break a com's long method call ( by setting duration)

Question

C#.2

iam converting word document's into pdf, which involves com dll.
 
1. iam looping all documents
2. open a word document and save it as pdf
3. during the step 2 most of the documents get converted successfully but some documents takes long time to convert or even shows some user messages. if it happens i want to terminate the document and continue with next document, since it is automation process with no user interaction.
 
my probelm is that i want to know, is there is any way that i can set some duration limit to break the calls (doc.open and doc.save)
 
 
karthik