resharper “cannot resolve symbol absmiddle”

Question

I have resharper 5.1. When I analyze "Errors in Solution" I get a lot of the same error in my aspx files. The error is:

cannot resolve symbol 'absmiddle'

It occurs on a line of code like this:

<img src="image.png" align="absmiddle" />

How do I suppress this 'error' so it doesn't come back on when I restart Visual Studio?