I uniinstalled FS9 recently and now cannot  re install the programme.
Following installation when I try to open FS9  I get the message Could not load dll! Flight Simulator will now ext..  I re installed a new version of XP and tried FS9 again with the same result.
Is this a computer problem or an FS9 problem.
Thanks in advance.

When you uninstalled it did you remove all of the folders and delete the fs9 cfg file?
If not i suggest you uninstall it again delete all folders and delete the FS9 cfg file. reboot your system and start from scratch.
When you uninstall fs9 it leaves the original folders and the fs9 cfg file can load dll files if you look at your fs9 cfg file you might have a section like below
[OLDMODULES]

FSsound.dll=1
SOARRec.dll=1
these could be the files it could not load as they are part of a aircraft cfg file
FSsound is used by some gauges and I am almost certain are not in the default aircraft.