When I try to do some actions in JIRA (v5.0.1), for example:
- Save a new filter
- Bulk edit of some issues
- many more
Session expires after a few seconds (seems like 3) and basically I can't do them. Note that I've also checked the "Remember me" checkbox logging in. I've tried to change the default timeout to "3000" but without success. Unfortunately, some necessary features are nearly unusable because of this problem.

Here is a couple of lines from the log file that are maybe relevant:
2012-10-01 11:07:06,355 http-8080-15 WARN <MY_USERNAME> 667x19093x2 g411ns <MY_IP> /secure/views/bulkedit/BulkChooseOperation.jspa [action.issue.bulkedit.BulkChooseOperation] Bulk edit bean unexpectedly null. Perhaps session was lost (e.g. when URL used is different to base URL in General Configuration)?
2012-10-01 11:10:35,474 http-8080-1 WARN <MY_USERNAME> 670x19142x3 1438g2d <MY_IP> /plugins/servlet/gadgets/makeRequest [http.impl.client.DefaultRequestDirector] Authentication error: Unable to respond to any of these challenges: {oauth=WWW-Authenticate: OAuth realm="http%3A%2F%2F<SERVER_IP>%3A8090", oauth_problem="consumer_key_unknown"}
Note that base URL used is the same configured in General Configuration.
On the same server are also installed Confluence and Bamboo, and the same problem applies to them too. For example, when I edit a page in Confluence I have to save it 2-3 times because the sessions seems expired.