Ie conflict with Mozilla downloads?

[The Wassermans]

I successfully downloaded Thunderbird and have been using it.  IE closes 
down when confronted with a subsequent attempt to download a dictionery 
for Thunderbird.  So I figured that I should download Firefox and use it 
to download my requirements but IE jacks up at that too!

I am sure that if I was in Ubuntu it would all work but I am still in 
transition and want to use my Windows for a while.

Anyone got an explanation?  Solution?

Dave W