ms office web access times out

I've got a couple of users who's office web access times out after about 5 minutes. I don't much experience with ms office, so this is probably a simple fix. Could someone tell me where I can find the 'logoff after ...' setting. (if there is one)

Thanks, Aaron

 

Anybody?

 

What do you mean by "office web access times"?

 

It 'times out'. If the user is inactive for a set amount of time, they are logged off and have to log back on when they want to return to thier account. All of our e-mail is handled at corporate hq, so I am thinking it is a policy and can only be changed by making a request and justifying it.
Does anyone have any insight into a problem like this?
Aaron