I don't know that I have a "fix", but here are some things to try or consider:
1.) Did you check the md5 sum of the 64-bit .iso you downloaded? (http://releases.ubuntu.com/raring/MD5SUMS) A corrupted download or a compromised HDD can result in broken installation media. (Speaking of which, using the Disk Utility, is your office PC's HDD SMART Data good?)
BTW, you can check the md5 of a file by opening a terminal (Ctrl+alt+T), change directory to the folder of the file (type: cd
path/of/file/), then type
md5sum filename.iso. (Insert the correct folder path and filename as needed, of course.) You can copy, paste, and compare the result in a text file with the md5 provided by Ubuntu/Canonical. I keep all of my .iso files alongside such a .txt file.
2.)Assuming the .iso that you're using for your install medium (CD-R/DVD/USB) checks out, can you find updates using the live environment (i.e., running from the installation medium)? If not, you may have a faulty USB, disc burner, CD-R, etc. There used to be a "check disc integrity" feature after booting an install disc, but I don't know if it's still available, or if it's automatic now.
3.) If it does access updates in the live environment, you may be best off reinstalling your office system. I've not reinstalled a new Ubuntu system, but I presume the old behavior is still true: installing over the same partition without formatting will clear and replace system files, but not /home personal files. Please VERIFY this and BACKUP your files [to another location] if you have anything that you cannot lose.
I hope this is helpful.