I have a source which goes like that:

 

zzComptes OR Comptes

 

When I refresh, IQ rewrites it to be:

 

[zzComptes OR Comptes]

 

... and then gives me the error :  "error reading data. Check source, filter, etc."

 

 

The work around is to write my source as : [zzComptes] OR [Comptes]. I don't know if that is a problem with that specific grid or what... but just thought I'd mention it...