Hi,
I cannot see your WSDL so am baseing this on what I imagine could be the issue(s).
Firstly, opening the WSDL in a browser might be OK since, the browser may interpret the WSDL as HTML, rather than XML and therefore not validate it for correctness. If is in your WSDL, that is valid HTML, but not XML. SoapUI is certainly having trouble parsing the WSDL content as standard XML judging by the error.
Also it may be possible that your WSDL imports XSDs that allow the use of nbsp to be valid, sometimes the schemaLocations of these XSDs may be unavailable to SoapUI e.g. if they require proxy settings to be confgured in order to download the XSDs.
I hope this makes some sense and isn't too off-beam? Like I say I can't see the WSDL, so cannot inspect or test it etc.
Cheers,
Rupert