You are getting this because "&" is a special character in XML and the grid files are stored as xml.
If you use the built-in editors for tasks, it converts the & into the "&" string that XML needs. But if you type the "&" directly in the source, then it does not get replaced, and DashBoard will throw that error.
So you can do one of two things:
1. Use the built-in dashboard editor to edit your tasks.
2. Use "&" instead of "&" in your tasks. Also, if you use "<" or ">" anywhere in your scripts, you would need to use "<" and ">" instead (which stands for lesser than, and greater than).
#DashBoard