I've tried some experiments:
(two mobiles: my SE k800i and a SE k750i of a friend of mine)

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Experiment 1:
- k800i in listening mode (server)
- k750i connects to server (client)

First connection: ok
Second and more connections: error

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Experiment 2:
- k750i in listening mode (server)
- k800i connects to server (client)

First, second and more connections: ok !

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Experiment 3:
- k800i server+client app
- k750i server+client app

Setting k800i to server, k750i to client
..first time: ok
..second and more: error
Swtich (k750i server, k800i client)
..ok..ok..ok..
Switch (k800i server, k750i client)
..ok..error..error..
Swtich (k750i server, k800i client)
..ok..ok..ok..
Switch (k800i server, k750i client)
..ok..error..error..
Swtich (k750i server, k800i back to main manu and do nothing)
Switch (k800i server, k750i client)
..error...error...
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So, it seems that this problem appears only for certain products.

And, after I started my k800i the application, when I connect to another server, this solve the problem for one connection.
The error appears only for two sequentially server accept!

__________________
cheers
Aman