I cannot access rules and alerts

HI,

I am currently experiencing problems trying to access my rules and alerts.
When clicking on rules and alerts i receive an error "The operation failed.
An object could not be found." this i assume is impacting my out of office as
well. When trying to set my out of office i receive an error "Your AutoReply
message could not be displayed. The client operation failed".
Secondly when i insert my text in the out of office field i receive another
error "Changes to the rule could not be saved. There is not enough memory or
the rules are to complex. Try deleting some rules.

As i have just mentioned i cannot access my rules to resole this problem any
help would be much appreciated.

Thanks