My first two installations of Office 2010 went very smoothly, however the third was definitely not a charm. During the installation I ran into two errors.
Error 1310. Error writing to file: C:\Windows\Installer\21c0d0.msi. Verify that you have access to that directory.’
Error 1935. An error occurred during the installation of assembly component {4FB1241B-9730-4DF1-B83B-1E9CFB73AAE4}. HRESULT: 0x80070005.
The second error caused the installation to fail and abort. Even running the install as administrator did not result in success, though the first error was resolved by doing so. Each time I ran the install it would fail at a different place in the install.
Eventually after rebooting many times and disabling various applications such as Carbonite and retrying it finally succeeded. I subsequently found some blogs complaining about similar problems during install of the 2010 office beta. The applications that seem to come up on the blogs are Panda AV and Microsoft Security Essentials. I do run Security essentials on all the three computers I installed Office 2010 on, so the problem would appear to be somewhat random, but I suspect security essentials contributed to the problems.
My advice to those installing office 2010 is disable security essentials (and other applications) and be sure to run the installer as administrator.
Update 2010-05-01
The final version of Office 2010 also suffers from touchy installation problems. The best course of action for office 2010 installs is to
- Disable Real-time scanning in Microsoft Security Essentials. (See below)
- Clear up any temporary files using CCleaner. (See below)
- Pause Carbonite
- Run the install program as administrator.
Be sure to uncheck the real-time scanning in Security Essentials
Use CCleaner to eradicate all temp files on your system
If you had installed 2010 Beta, be sure to unistall all office products prior to install.
Upgrading from 2007 can also be problomatic, best to do a complete uninstall first.
JPWhite's Tech Blog 
Thanks for the tip..I have been having the same general issue since moving to windows 7 and MS Security Essentials (MSE). I also have Carbonite. I had a horrible time a while back installing SQL 2008 on this fairly new laptop. For this installation of Office 2010 I disabled real-time scanning in MSE, and also in MSE put in an exclusion for the c:\windows\installer folder just for good measure. I also paused Carbonite. The 2010 install was successful following that. For anyone else reading this, remember to re-enable real-time scanning and remove the installer folder exclusion in MSE, just to be safe.
I’ve found that the solutions above didn’t work for me alone, but clean booting Windows (MS KB 929135) as an additional step did.
I struggled with this for weeks and for me uninstalling carbonite was the key. I have actually decided not to bother with carbonite as it just slows my pc down way too much.
A good alternative to Carbonite is Mozy.
I really got frustrated due to installation error that appears during installation of MS Office 2010, it took nearly a week or so to find a working solution to fix the problem, here it is: http://backspacetab.com/2011/05/17/ms-office-2010-installation-problem-2/
[…] Office 2010 Installation Woes | JPWhite’s Tech Blog – Error 1310. Error writing to file: C:WindowsInstaller21c0d0.msi. … If you had installed 2010 Beta, be sure to unistall all office products prior to install. Upgrading from 2007 can also be problomatic, best to do a complete uninstall first. […]