InfoPath Dev

I need to open an XML file created by InfoPath Forms Services but cannot.  Some forms appear in the form library explorer view with the correct InfoPath icon - those can be opened in Notepad.  Others do not display the proper icon and will not open in Notepad.  We receive the following error message: "The filename, directory name,  or volume label syntax is incorrect."  I have tried opening these files with many applications without success.  Anyone else have this issue or can make a recommendation?

 well i think i face a similar issue long back -> some forms didnt show proper icons. i found that an issue of addition of null characters at EOF. but they used to open properly in notepad or any xml editor. can you attach a sample form so that we can find out what is wrong with these forms