A syntax error means that you have made a mistake while creating your PHP structure. You could, for example, be;
■ Missing a ; at the end of an individual line.
■ Using curly quotation marks.
■ Missing a curly bracket.
When this error appears it will tell you which file the error appears in (functions.php for example) and approximately which line (it may not always be the exact line so be sure to check just before and just after) in the code.
If you are receiving an error which says 'parse error: unexpected' this usually means that you have forgotten to include a character.
If the above info does not help to resolve the issue:
Try changing to the default theme and see if the problem disappears.