9 out of 10 times it's a software issue... your script(s) is most likely running poorly optimized queries overloading your sql server... moving to a different host most likely will not solve the issue, you need a software engineer familiar with mysql to check it out first...
If you are willing to invest a few bucks, I can look into it for you, icq: 33375924 or email me at woj#at#wojfun#.#com to discuss details...