Greetings, as the discussion title says, i'm having this strange and most anoying trouble, When i'm playing with distortion(no matter which amp i choose) after a certain (variable) time i loose almost all my gain, and the sound goes almost clean...

This can happen after 1 minute after i start playing or 5, or 10, but it always happens! Does anyone knows the reason for this, and if so, what is the solution?! This is very anoying, and it basicaly makes it impossible for me to "play normally".

Note: I live in Portugal, so it wouldn't be easy for me to send this to a "official" repair center. Sorry for my English...