And it is not a problem with the sdlxliff file. I opened the sdlxliff file in UltraEdit and parsed it - everything well formed. It is the target file writing problem.
The standard solution to these issues is to massage the source document and try again. Open the source docx in Word, save it as rtf, then import the rtf to Trados and see if it exports correctly.
BTW the error refers to line 1, position 144, i.e. the 144th letter (character) in the first line of the sdlxliff, which is a double quote character that shouldn't be there according to Trados. You can have a look and try to fix it but diddling the source document has a better chance of working.