Error comes and goes

[PHPmaster]

Hi, I have a phpwcms1.2.6 website that was always performing o.k. Now after a year or so, I have this error sometimes when I click in the horisontal menu. This is the error:Fatal error: session_start() [function.session-start]: Failed to initialize storage module: user (path: /tmp) in /usr/local/psa/home/vhosts/xappix.nl/httpdocs/index.php on line 47

It's not every time but 1 out of ten which is still too much if you ask me.
Does somebody know what this is and how to solve it?

Thanks for any advise.
Jeroen

[Oliver Georgi]

ask your provider.

Oliver