Serial port and Apro exception (Kicked M$S and now solved)

[#1]

I have XP SP3,  three programs that use a serial port,  since yesterday morning i have been getting the following message.
Unable to Opens Selected Com device - Apro exception
I last used it on 30th and no problem,  I had done a trial of Tass Books onto a new Maxtor external HD, now uninstalled Tass Books and unplugged external HD.  Also tried a system restore to 29th.  No Change.
My next move I have got two USB to Serial adaptors, but have got to find them in my pile - but would like to still use the com port.  Any ideas

[#2]

'Apro' seems to relate to this http://tpapro.sourceforge.net/index.html , Async Pro.
Have you previously used this or was it installed by Tass Books ?

[#3]

I could not find that program, tried the System delete, no, active progs no,  went back to system hardware and disallowed com 1, then tried as thought the progs didnt like it, went back to system hardware and enabled, via a small wizard, AND IT WAS OK   
All an M$S Mystery