Database Problem

[matatug]

Hi,
I have an vbulletin forum site.it has 27 000 members.I bought a server for 1 site .I saw plesk and The site use %98 of ram.Forum's database is 300 mb
Server
Amd Sempron 2600
512 mb ram
Plesk Control Panel

Altough there is 1 site,it says generally "database error".Nowadays There are 6 members in the site but after 10 min. it said database error again.What can I do

[Alan @ CIT]

What database errors does it give you?

Thanks,
Alan.