My Windows 7 x64 Home Premium machine has started behaving oddly — links from programs other than web browsers do not open a web browser as you would expect. For example, links in emails in Thunderbird, in tweets from Tweetdeck, and links in Steam descriptions all do nothing. I get no errors, no other programs popping up, nothing.
I've reset the control panel defaults so my browser of choice (Iron) handles all the things it's capable of, to no effect. Unfortunately I'm not sure how long this has been happening — I just noticed it this week but I don't actually use Thunderbird on this machine much, so it's hard to pin down whether it's something I've installed recently, a Windows update, or something else that's caused it.
The only hardware change I've made recently was to remove a bad stick of RAM — I can't imagine how that would cause this.
Any insights appreciated.