What kind of box do you have?
I have an old x440 that gave me nothing but problems with ESX 3.5 Update 1/2/3. The local disk (controller obviously) would crap out, and the / file system would become readonly.
I did a reinstall with ESXi 3.5 Update 2, and haven't had any trouble out of the box.
I know it is unsupported, but for that matter ESX 3.5 is unsupported on an x440.
Jase McCarty
http://www.jasemccarty.com
Co-Author of VMware ESX Essentials in the Virtual Data Center
(ISBN:1420070274) from Auerbach
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Jase McCarty - @jasemccarty