Many thanks for that, Mac.

Pleased to report that the sys restore operations went just fine. Restored back to a point (10 days ago) and then back to now, but I still had the same loss of real time effects at every time.

The DX tests all seemed to be fine (report below) and I haven't noticed any other sound-related problem.

Looks like I'll have to move on to the restore default option in the PTPA programme.
THe PGMusic assistance chatline mentioned that this can be achieved just by deleting a couple of files (I shall have to be reminded of which!).
So I guess you try the oldest trick in the book of keeping the existing files, renaming them oldxxxxxx.ini or something similar and moving them to another location. That way they can be recovered and returned to the orginal folder if needed.

Just for info. you can get the sub-categories of the Track Category Audio Effects to appear or disappear by, respectively, authorising and not authorising indexing of the main Power Tracks application folder.

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System Information
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Time of this report: 4/25/2009, 21:38:19
Machine name: GLINERT-FD6F496
Operating System: Windows XP Home Edition (5.1, Build 2600) Service Pack 3 (2600.xpsp_sp3_gdr.090206-1234)
Language: French (Regional Setting: French)
System Manufacturer: System manufacturer
System Model: System Product Name
BIOS: BIOS Date: 07/12/06 20:51:41 Ver: 08.00.10
Processor: Intel(R) Pentium(R) D CPU 3.40GHz (2 CPUs)
Memory: 3072MB RAM
Page File: 510MB used, 3940MB available
Windows Dir: C:\WINDOWS
DirectX Version: DirectX 9.0c (4.09.0000.0904)
DX Setup Parameters: Not found
DxDiag Version: 5.03.2600.5512 32bit Unicode