Umm...I am not sure,but everything works now.There are some important stuff that might get disabled which results in plugin installation failure.Check the following:- Type in "Chrome://plugins" without the quotes in your address bar and hit "Enter" button- Check if the "Microsoft DRM" & "Default Plug-in" are disabled.- If so then enable them both.- Now go ahead and install extensions,you'll be fine.I somehow want to believe its the webstore. You see when 1db1 earlier reported that his friend could install extensions I went to webstore from a link in evernote newsletter & as you know everything worked from then on. I think it was a momentary problem with webstore itself and since people doesn't install extensions every day,very few noticed it,meanwhile google fixed it. It could be your DNS too,sometimes various ISP block addresses with the words "store","buy" & "getrich" etc to help users avoid online scams,its a rare case but not impossible,try changing your DNS momentarily to install extension and then revert back.Thanks

None of the above has worked. Nor has uninstalling, deleting all install files, remove extensions from google sync, uninstalling all extensions, reinstalling chrome, changing the localtion on my disk for app data, etc, etc. This is getting really frustrating.