Excel 2007 Read-ony issue

recently after I opened an excel file that I have been using for sometime
now. I made some modification to the content of a spreadsheet. When I
attempted to save it i get a read-only restriction. i attemtp to save as
under a different name and it does it again. now I cant save my changes and I
dont want to loose my work. I have tried clicking on the properties box and
have removed the check in the read-only box. then close but it continues.
last time I ended up cutting and pasting the excel into a word document just
so I could save it. any ideas?? i have tried to save it in the 2007 version
as well as the 2003 version as well????