I have same issue, I can be clicking through pages then get logged out or I can just be open looking and it will log out, so it's not down to non activity on the site as it happens while browsing
I have a 1024 m plot for sale 351 prims available for a low price of L$1337. At this price it is cheap and probably won't last long so if your after your first plot on the mainland or just another for a small store then this could be for you
http://maps.secondlife.com/secondlife/Carlovitz/175/11/37
NOW SOLD!!!
GRANDFATHERED Full 20k SIM for SALE (Tier 195 per month - next due 26th Aug) $350 + $600 transfer fee
Contact Saybera Drake in world for more details
Also have a GRANDFATHERED Homestead for sale as well (Tier $95 per month)