I just checked through the forum, and the most recent thread that I found said that this would be fixed in vers. 3.7.1. I have been having this problem for quite sometime on one of my sites, and now it is happening on two of them. For awhile, I could work around it by changing browsers, but now, searching for plugins on either site, regardless of which browser I use, brings up an error message.
I can still manually install plugins, so it's not the end of the world. But is there any way to fix this problem?