Well that's strange indeed, why it locks... well it will lock anyways until you have some valid data.

You said you're using a MAX232 and you're capable of sending data to your PC... T2400 is the setting. Weird enough.. my computer don't work with such low baudrates...

Code:
serout portd.3,t2400,[#temp]
pause 1000
serin porta.1,t2400,pcsig
i would suggest to remove the pause 1000, and change your SERIN line


Code:
serout portd.3,t2400,[#temp]
serin porta.1,t2400,#pcsig