My computer stopped at "verifying dmi pool data" I found from the net a solution, in BIOS disabling external cache. But now what, can I buy new external cache for my computer, or do I have to buy a new computer, cause my computer does work, but after some time needs a restart, because becomes extreamely slow, or is there anything else I can do...

It appears that your external cache is faulty and the only way to fix it on your existing computer is to buy a new motherboard.