voltage problems

[shzmm]

hello i am new to this forum but have been building effects for a few years.  recently i finished making a version of the super tone control project by craig anderton.  it is about the fourth or fifth one i have made.  however the problem with this one is that as soon as the unit is on, the voltage drops extremely fast-- the positive supply drops to a negative value in a matter of a couple minutes and the negative supply drops as well albeit slower. 
i have checked over the traces many times and can find no stray wires or shorts, even when testing for continuity.
any suggestions on this tricky problem?
thanks

[R.G.]

Have you checked the pinouts for the actual semiconductors you're using to make sure that nothing is connected backwards and pulling the power supplies down?