Q6600 clocking problem after overheat

Okay, my problem: my PC hangs at the POST screen, after the scren that tells me my graphics card is OK, then beeps, and hangs when starting to display stuff about my RAM.

right below where it identifies my processor and its speed (Q6600 at 2.4GHz), it says "Memor" (the starr of "Memory Check OK" and then it takes say, 5-10 minutes to continue his sentence and boot normally...
If i then clock it back up to 3GHz, it reboots, goes back up to this page, and instantly reboots again to reset his CPU to 2.4GHz.

Now, not too big a deal perhaps, but i'm not fond of waiting that long for my pc to start up. This has been happening since my CPU overheated (it was running at 3GHz, and my Zalman Reserator watercooling somehow got bubbles of air into the tubes and this particular bubble of air had blocked water flow through the CPU block)

Any ideas?
Also, any ideas on how to prevent those air bubbles?