This could be because the feed was corrupted while downloading the first time. Try this.

1. Export your feeds to an .opml file by going to File >> Export Channels. Save your feeds to your computer.
2. Exit from the EM RSS Receiver
3. Go to "My Documents" folder and open "My Enterprising Mom RSS Receiver"
4. Delete the Reader.bin files. This will reset your reader
5. Re-start your EM RSS Receiver again