adobe reader issue-error message, cannot open explorer.exe

i am having a problem with adobe reader, i tried to download the free reader from adobe.com and it has taken over my pc. when i try to open windows explorer (or firefox) i get an adobe reader sign-in screen with the error message "adobe reader could not open explorer.exe because it is either....".

background: 12-29-2016 - i needed to create a pdf from a website and all i have on my pc is reader. i found a cd of adobe acrobat 6.0 std (i think i got it from an IT guy at work years ago-i am now retired). i loaded the cd (with a lot of error messages) and it took over my computer, as stated above. i uninstalled acrobat and still had the problem so i uninstalled reader also. today 01-05-17 i needed adobe reader so i downloaded it from the adobe website and the same problem is occurring. maybe some error code info remains on my pc.

so i called adobe calif. and was transferred to adobe tech help, spoke with prashand and he was unfamiliar with reader and suggested that i post on the forum.

thank you