I have Avast on one old XP computer, but decided to also install it on my Win7Pro laptop as a replacement for Microsoft’s WSE.
I found that if I clicked on an email address on a web page (or used the add-on that puts an email envelope link in upper right toolbar on Chrome), an error window popped up saying:
WLMail.exe - System errorThe program can’t start because WLDCore.dll is missing from your computer. Try reinstalling the program to fix this program.
That is nonsense, because the file is there.
I found various work-arounds on the web, but because this problem only showed up after installing Avast, I solved my problem by un-installing Avast. With no AV program the mailto links worked fine. Then I installed a different AV program (Panda) and again no problem!
Just posting in case it may help others.