.dll message with Firefox Mozilla

[FONT= "Verdana"][/FONT]Good Evening, all!
I'm brand new here so I hope you will excuse me if this has already been addressed and resolved in another area. I hope someone wise and wonderful can help me with a problem I'm experiencing with my Windows XP 2002 Home Edition. The computer is a Dell (DIM 2400) desktop that I've had for almost 6 years.

Every single time I turn on the computer, I get the same message (to paraphrase):

"Unable to locate component MSVCP71.dll. Re-installation may help.
reader_sl.exe "

I'll hit "OK" and then I'm able to get into Firefox Mozilla and onto the Internet and YAHOO to retrieve my e-mails.

I have NO idea what this means. Apparently, I had something that I no longer have. Fine, I'll re-install it if it doesn't cost an arm and a leg. But WHAT IS IT??

I switched over from Internet Explorer about 2-3 months ago because it was so s-l-o-w opening things. I switched to Mozilla Firefox and for about a week, I was pleasantly surprised by the speed. Then things started getting slow again. And last night, two times, I received a message from Firefox that I'd have to re-start my computer since everything crashed...TWICE!

It takes so long to get going on the Internet with the current situation, that, to kill time as I wait, I'll open and play a game or two of Solitaire.

We do have Verizon High Speed DSL, which would be ironic if it weren't so frustrating.

Can somebody please tell me
1) what ".dll" is, and why I need it
2) what is a RELIABLE way to re-install it?
3) If this were to happen to you, how would YOU solve it? Other than throwing the computer out the window, that is...

Thanks very much for your time and patience. I'm not a computer "nerd" so an easy and simple explanation will be vastly appreciated.

Enjoy your day/evening!

Vintage 48