Apparent problem -- solved.

[Diagonal]

Confession:

Part of original post was: "Using Uno board with an Analog Shield. What fixed resources does the Analog Shield library use? I have code that stopped interrupts from occuring by doing only #include <analogShield.h> , but the interrupts resumed after commenting out the include. This code was to establish a timed interrupt for accessing the Analog Shield, and I did not get to integrating in my analog access stuff."

Well, my problem was really stupid. I had a call to the lcd inside an ISR. Duh.

[rp-prew]

No problem is a stupid problem. I have definitely done the same thing when writing my own code. We really appreciate you posting an answer to your problem though. It helps us out and other users. Thanks a ton. Good luck with your project.