It seems some spreadsheet files has defined the Grid line color which is then 
used for this file instead of the default user definable one.

The grid line color in the spreadsheet might be a bad choice for some desktops/
users and they might (not surprisingly) prefer their own default set grid line 
color.

Please ocnsider to add an option for "Always use default grid color" so that no 
matter which grid color the user who saved the file had/used, the default user 
configurable Opoen office Calc grid line color is used overriding what's in the 
document (but not save this user defined color into the document).

I see this as a request for a user to view files the way she wants to - and not 
make other users decide for her.

Cheers
- David