Could you post any error messages/prompts from cgminer or guiminer whenever you connect to btcguild pool?
cgminer-using a config file with three different pools, cgminer will start, but btcguild is listed as dead. Running it clean from a command prompt it says pool setup failed, works fine for eclipsemc though.
guiminer-Cycles between "IO errors -1, tolerance 2" -> "IO errors -2, tolerance 2" -> "No more backup servers left. Using Primary and starting over" And repeat.