Regardless of the floor texture I attempt to make it appears to have a very dark shadow over it when I import it into the game.
I have all EPs up to FFS.
I didn't have a problem like this before and all the floors I have created are still okay.
I do not have a problem with wallcoverings, just flooring. To double check that it wasn't my graphics programme I also have just exported and imported a floor without modification to see what would happen, and the heavy shadow was over the 'unmodified tile'.
One thing that I did notice on creation of one tile that had a heavy over shadow is that when shadows of sims appear their shadows are a weird light blue.
Can anybody help me?
I have uninstalled and reinstalled Homecrafter Plus many times for the same thing to keep reoccurring.

First, try updating your graphics drivers:
http://www.modthesims2.com/article.php?t=146389

I have updated my graphic drivers, the problem still remains

Have you tried tweaking the brightness and contrast settings? Also showing us an image of what you're seeing may help.

Apologies for not returning sooner, been on a boozy weekend break
I've tried tweaking settings, no joy.
Pics....I don't have a web page and am unsure how to import the pics. I have took several shots before after and how it should have turned out (tweaked)

Do downloaded tiles behave in the same way?

No, nor do tiles that I have previously made. I cannot recollect when it started but I think I used the newer version of Homecrafter...I had to do a full uninstall and reinstall about 2 months ago and then updated Homecrafter....but can't get the original Homecrafter to see if that is the problem.

Did you change any of your drivers, or did you install any other programs just before this started to happen?

I didn't install new drivers but I did install Theme Park III on a fresh drive whilst I was waiting for discs to be replaced.
What happened my game went real weird on me. So I did an uninstall, reinstalled to find it go even weirder, only to discover that the first disc of the base game had cracked. EA games replaced my discs very fast but the first batch of discs wasn't compatible with each other. Ended up being a full format of my main drive and a fresh install. Lost my original homecrafter and had to download a new one. I had everything else backed up on a separate drive. Took me a while to discover about the strangeness of the floors
What I don't understand is why the game displays floor tiles that had been made prior to all this perfectly and newly created tiles its as though there's a layer of black on them

Okay, just to rule this out, cut and paste your Sims2 folder to the desktop, and run the game to force it to create a new one. Now try the tiles- do they look the same?
http://www.modthesims2.com/article.php?t=139718

Its looking to be something in my downloads folder.
I did as suggested and there was no problem.
Placed my downloads folder back, and the problem was back.
Suppose I'm now going to have to go fishing in my download folder to discover the problem now.
Thankyou very much.

Hopefully this will help:
http://www.modthesims2.com/article.php?t=139702

Thankyou very much for the assistance.
Came down to the last 20 files and said stuff it and deleted them
Game now appears to be running sweet

Excellent, nice work! We learn something new every day, this one was interesting.