I dont think there is any real solution, it sounds like it's simply coming to the end of it's life, it happens to the best of us all eventually.
When my last ps2 did the same thing, i was actually able to get in touch with sony and get it replaced,and there were no questions asked regarding it's warranty, which was just as well,it's going back some now,but i'm almost certain it was outside of its warranty.
Hopefully you will get a bit more life out of it yet, but i think its inevitable that its going to need replacing pretty soon.
Sorry to bear all bad news.