Hyperlink in Excel 2007 lost

Please help my job depends on it. I use this spreadsheet that my boss built and it has hyperlinks to directories on the network. The hyperlinks would go to sub-directories in either the north or south directories.
That being said at random times they stop and we'll receive errors that the path is invalid, or they will change and point to a local directory on my computer (c to directories that do not exist on my hard drive. He's constantly telling me I'm doing something wrong and I haven't touched anything. The closest thing I did was put two shortcuts on my desktop to get to the north and south directory.


u:\techops\2011\cent west\Spreadsheet.xlsx
u:\techops\2011\cent west\maint\north
u:\techops\2011\cent west\maint\south