Live with Walkman - Network connection problem(internet disconnects frequently(every 2 min))

[rhs]

From last 1.6 years I am using Sony Ericsson Live with walkman. I dint had any problem. Now from last 1 week I am having network problem. Internet disconnects evey 2 min.I cant download and i cant check mails also properly.Changed sim and checked still same problem.Need help

[Alexander1]

Try to change the network mode under settings > more... (wireless and network > mobile network > network mode. 

If that doesn't help I suggest that you update/repair the phone software using PC Companion: 

http://www.sonymobile.com/update