the only way to clear a Session is to delete everything in the session, or load one of the default sessions numbered 1001 – 1008.
the only way to clear a FX Chain is to delete everything in the FX Chain, or load one of the default template FX Chains numbered 1601 – 1615.
not sure what to say about the strange bugs though.. check the FX Chain Parameter pages to make sure the I/O levels are all at unity?