TC35 DEV Board

hi all,

iv recently brought one of these Siemans TC35 dev boards from ebay

http://www.ebay.co.uk/itm/GSM-SIEMENS-TC35-SMS-Module-Board-RS232-UART-Serial-Arduino-Voice-adapter-UK-/271016857401?pt=UK_BOI_Electrical_Components_Supplies_ET&hash=item3f19dd0f39

although this is not the exact one its very similar.

the prob im having is that if i have my arduino connected up at start up it seems to slow the arduino to a snails pace. as soon as i disconect it runs fine.
if i leave it disconnected for a while and then plug back in, say after 20 secs it runs as normal.

im guessing that the TC35 needs a while to set up?

iv tried putting a delay just before i start the connection to the Serial port (SoftwareSerial) however it makes no difference.

has anyone had this before? many thanks

spriggsy