I guess vps.net is a hosting company? So start off with the type of
account you have with them.
What webserver are you running?
What OS is runnign your webserver?
What crashes/freezes? The website? There is a difference between
crashing and freezing, namely that a frozen system will unfreeze
without user intervention.
You say the problem occurs at regular intervals, what is the pattern?
can you trigger it yourself?
Where is the error message coming from? webmin admin interface? webserver log?
Also have you already spoken to the hosts support dept? what did they say?
toby