PC2870

Most likely reason is you are using a function in the formula that is not one of the standard ones in 2007. Go to Tools addins and enable the addin that contains your function. Analysis toolpak would be a good start.

Unfortunately in MS opinion if you don't have the install discs then your copy is not strictly legal. Hence the reason they put the key on the disc case with a message to store in a safe place. You might have to harass the former Office manager to disclose the location of the discs if you need to reinstall the older Office software! However if Office is already installed on the computer you should be able to use the upgrade path. Office2007 will ask when you install if you want to keep or upgrade the existing office installation. Upgrade overwrites the existing installation.

I agree with sparhole. I have been running Avast Home edition for over 3 years now. It is totally free, doesn't hog resources, updates quickly (even on dial up) every time you connect to internet. It can be used for 14 months before you have to re-register it. You can even use the same rego key on 2 home computers. The only "problem" I have ever had was a possible false detection of a trojan in CPUZ install file. Up[censored] to latest CPUZ fixed issue. And yes it has captured and quarantined some viruses inbound in email. The standard skin is a bit ordinary looking but there are many other skins available now. It has modules to protect emails with outlook and webmail clients, instant msgr, P2P, as well as web shield. Check it out at www.avast.com

I realise this post is a long time after the question, but my solution may help some other readers who have the same problem. I also had the same problem, but instead of reinstalling etc as some suggested I was able to fix by browsing with IE to a network folder to load A43 file manager (which doesn't need to be installed). Then used A43 to opening a command prompt. Type MMC to load the console. Then add group policy editor and reverse all the settings I had enabled. In hindsight it may have been also possible to browse to C:\windows\system32 and load cmd.exe but I think my local drive was locked out by group policy. I had disabled the Run box though so getting to CMD by normal means was not possible. A43 file manager worked for me anyway!