Calls disconnect once put on hold

Hi, Im still learning about Asterisk, So far have found it very good. But have a config problem.

Whenever a external call is put on hold it is disconnected.

The Tranfer and Xtfer also disconnect the call.
When calling internal extensions i can place them on hold and works ok…

Ive tried to find solution but dont really know where to look anymore.

Im running asteriskWIn32 1.2.14 with cisco 7940 phone v8.12

When i press the hold button the call disconnects and the following is displayed by asterisk:

WARNING[6932]:rtp.c:462 ast_rtp_read:RTP Read error: Connection rest by peer. Hanging up now.

Hope someone can help Thanks!!