Runtime Error and Back Web Client

Hello,

I am having some problems with my computer. I have a Dell Dimension 4550. These are the error messages I am getting when I start my computer up. I don't know what these both mean? Can you help? After getting these messages (number 1 pops up everytime I turn on my computer. Number 2 popped up once)-- I would be on the internet and have like 3 screens opened. Always one would get locked up and I would have to reboot.  

1.) Microsoft Visual C++ Runtime Library

Runtime Error! Program:C\Program Files\Internet Explorer\IEXPLORE.EXE

This application has requested the Runtime to terminate it in an unusual way. Please contact the application's support team for more information.

2.) Back Web Client

BackWeb is unable to access its data directory. Either the data directory is invalid, unreachable or there is another instance of BackWeb accessing it.