I ran into a problem printing from IE8 protected mode to a networked HP printer where it would freeze IE and lockup printing.  I had 2 computers act differently with this problem.

The first one where the issue was reported would lock up not only IE but also other printing.  After the crash, the print queue would not act correctly.  Printing test pages would give me an error saying that the server was not responding and that I needed to reboot it.  Other people could still print and test prints originating from the print server would print.  I also could not add new printers while this was happening.  Relogging did nothing.  a full reboot would return things to normal until it locked up later.

After a few crashes, we connected it to IE8 printing.  With a little more testing I discovered it would print fine with protected mode off but failed with it on.  We are trying our hardest to run secure by default so we want this protection.  Too bad it protected us from printing.

I returned to my computer and mapped the printer to my computer.  I was easily able to reproduce the problem.  My print spooler recovered better and I could print other things, but IE crashed hard every time.  I did a little hunting on the web and had a hard time finding content on topic.  Here is what I did find.

When IE runs in protected mode, it runs with limited privileges.  In my case the print driver wanted to run an exe from a location that is restricted by those privileges.   With that in mind, here are your options when faced with this problem.

1) Turn protected mode off
2) Run IE as administrator
3) Reinstall with a basic driver
4) Install printer locally (skip print server)
3) Don’t print to that printer
4) Create rules to elevate the processes

Some people are able to install more basic drivers but that is hit or miss.  On my computer I was able to install it locally avoiding the print server and it worked fine.  That was an interesting detail.  Our print server is server 2003. 

I was able to resolve the issue by creating a rule to elevate the processes needed for printing.  The post that gave me this idea is here. I did exactly what was suggested and it fixed the problem.  There are registry keys for IE that tell it what to elevate under protected mode.  I created a rule for the same 3 files mentioned: HP1006MC.EXE, HP1006SM.exe, P1006SSL.exe.  After closing IE one more time, it picked up those rules and it worked fine.

I exported those keys to reg files for more testing and it worked on the original computer that the problem was reported on.  I merged those settings into our domain policy and I hope that’s the last I have to deal with that. 

I found those files in the C:\Windows\System32\spool\drivers\w32x86\3 folder.  If I have more problems like this, my plan is to create a rule for all the exe files in that folder.  I was able to do the exact same 3 that the other guy mentioned.  If the problem continued, I was prepared to make rules for all 10 files I found.