Error “The linked file was unavailable” in PowerPoint

Hello guys,
I have MS Office 2003 installed in my desktop computer. I am using PowerPoint for my upcoming presentations these days.
A day before yesterday, my co-partner (for presentation work) made a link in order to update the files of the presentation.
But yesterday when we tried to click the link, we received an unknown error message which states:
The linked file was unavailable and can't be updated

We searched this issue over the internet but of no avail.
Can you please give some idea on how to fix this issue? Our presentation is quite important.
Waiting for your reply!
