MSP430 debugger doesn't work...

Customer asked me to add a feature to an older product, so...

On 32-bit Windows 7, I'm using:
CrossWorks for MSP430 .
Release 2.2.1.2013112503.19841
Windows x86

The debug probe is TI MSP-FETU430IF V3.
Target processor is MSP430F5310IPTR.

Crossworks connects to the chip and flashes/verifies AOK.

Attempting to run/debug doesn't work, Crossworks sometimes hangs/crashes.
It says processor is running, break-points do not work,
sometimes its possible to pause execution but inspection etc doesn't seem to work.
Also, IO on target is sometimes interfered with (ports aren't read correctly by app, etc).
If I flash target, disconnect debug probe, then power-cycle target, target runs OK.
But no joy trying to use debug tools.

Anybody got any ideas?
Thanks,
Best Regards, Dave