Stacey,
Sorry that you are seeing this issue. We could not replicate the issue at our end on Ubuntu 14.04.
Can you please answer some more questions for us ?
1. How did you install MyEclipse ? Is it using offline installer/ custom installer/ archived update site?
2. Please share the Installation Details from MyEclipse > Installation Summary > Installation Details.
3. Please share details about the specific plugin you are trying to install along with the steps you are following to install it in MyEclipse.