Need a program that searches within text files in a directory

Hi all, this is hopefully an easy one.
I'm looking for a windows program that can search through text files in a directory for a string of text and show the results of which files contain that string, and preferably where in that file. Currently I'm using Windows Grep for this, however it routinely crashes and gives out of memory errors. There hasn't been an update for that program in about 2 years, so I'm not hopeful of a bug fix coming soon.

I've looked at notepad++, but you need to actually open all of the files you want to search. We currently use Windows Grep, but it crashes alot.

So again, here are my requirements:
1. Search within text files in a directory for a specific string
2. Displays a list of files that contain the string
3. Allows you to open the files from the list and see the string