Paypal, Wiznav, Thickbox and categories not working after upgrade to 1.4.2.5!

[T-bird]

I really need to remember that old saying, "if it ain't broke, don't fix it"! Every time I upgrade I have major problems, but this time is definitely the worst.

So I upgraded from 1.3.6.0 to 1.4.2.5 and now the Thickbox feature doesn't work. If you click on the picture nothing happens (posted about this before but didn't get any responses).

When I log in under my test account half the categories in the categories block disappear, though they are all there before login. I tried uninstalling and re-installing the module but that didn't cure it.

Wiznav works fine until you look at a product page then it disappears and is replaced by links stacked on the left hand side.

And finally, two of my customers have reported they are unable to connect to Paypal from my site. Fortunately they contacted me so I didn't lose the orders, but I need to get this fixed before I do start losing orders. Works fine for me and other customers however.

Anyone else have any of these problems and could offer advice?

Think I'll stop installing upgrades...!

Thanks,
Andy
www.thunderbirdmodels.co.uk