One of the most nightmarish experiences for a support engineer is when you have a hysterical customer yelling at you on one end on a possible bug while the sustaining/dev team asks for a reproducible case on the other ! At first, I used to get frustrated ( in my previous job with a different company as a support engineer) but slowly started to get used to it and understood that for a developer, his/her code is never at fault! 
Now that I don't face the customer song anymore directly, I can look back at it with a smile. The Dilbertian view of the the process that we support engineers had is best captured by the song from Melanie's blog:
"
Tell them it's a feature,
Say it's not supported
Change the documentation
Blame it on the hardware
Find a way around it
Say they need an upgrade
Reinstall the software
Ask for a dump!
Run with the debugger
Try to reproduce it
Ask them how they did it, and
See if they can do it again."
I am sure every support engineer has a classical Dilbertian experience and if you happen to be one, do share it!
Ah! Developers!!