Why won't my computer charge from any charger?

My MacBook Pro (OptiBay'd but besides that mint condition) has periods where it will not charge. I have tried using other chargers and other outlets and it just does not charge at all. The MagSafe adapter light stays off too, and jiggling the cable around does not help. Then, eventually after seconds or many hours, it works again. This started off only happening occasionally but now has been happening for ~8 hour periods with only a few minutes break.

Other symptom is that I keep having random shutdowns where when my computer boots up again, my clock is reset back to 2000 and my Airport needs a password again. I have tried resetting the SMC/PRAM (dunno if that worked though).

Please help! What do I replace or do?