Sounds like your old config didn't get upgraded perfectly.
You'll need to manually remove "bqbackslash" from your user.cfg.xml:
<colorcoding_profiles n="colorcoding_profiles.C Shell" version="?">
<styles v="... dqbackslash"/>
</colorcoding_profiles>
After removing the word "bqbackslash", save and reload your options when prompted. Alternatively, you could just delete the "styles" line since I suspect you haven't made any intentional changes to it.
