I have been using Tixati for ages fine but after a hard drive failing on me I've had to reinstall windows on a new drive. Now Tixati is downloading fine but won't upload/seed once complete. IT had worked fine with upnp previously but just to be sure I opened the ports that Tixati was using and checked they were open with a port sniffer but still nothing. Any help would be greatly appreciated.

Maybe create a torrent and ask a friend to download it and see what happens. If you are able to download without problem I think you should be able to seed too.

Well, I have noticed that it does seed but not constantly. It will seed at my full upload speed then just stop for a while, if I look at the peers there are plenty there but it keeps saying they are timing out.