1. How are you creating the PDF from Excel? Hopefully, you are selecting the "Entire Workbook" option from the dailog box that greets you when you've executed FILE > PRINT from within Excel.
2. Are you really running just plain version 7 Of Acrobat, or are you really running 7.0.1?
usually do not want the entire workbook, so I highlight say 4-5 worksheets within the workbook, then do file, print, and select adobe as my printer
And you've selected "Active Sheets" in the Excel print dialog box, right?
This is one time I wished I'd failed so I could at least see the end result you're getting. I'm sorry. :(
I have to agree with that statement, particularly because you said you have been successful some of the time in executing the process correctly.
Have you tried the inane stuff like cleaning out all your temp files, defragging, etc., etc.?
1: open excel doc
2: go to file>print select the adobe pdf printer
3: click on properties>layout>advanced check the page size make sure it's what you want.
4: click ok to go back to the Excel print dialog box
5: here select preview, check if the preview is good if it is print the excel doc to pdf if not continue to step 6
6: in the preview click on setup...
7: Under the page tab, set your scaling options, make sure the paper size is the same as in step 3 and as said loweer the print quality to 600 or 300 dpi.
8: click ok to see the preview again, if ok print, if not go back to step 7 to make further adjustments.
it might be that you need to repeat this for each individual worksheet in order to make sure they are set the same.