safari troubles

when ever i click a link for a download when using safari it never seems to download anymore.. it was working fine till about a week ago when now i try to click a download link i get resent to the same page i was on.. when i open link in new window i get this in the address bar.. ".SDPluginHelper.html" or something like that... what the hell does that mean, and also does anyone know how to fix this problem?

Cheers.

yeah i think i have but it says it has come to the end of the free trial and it didnt do that much to quicken it up so i havent bought the full version.
does that mean im screwed then?