Did you try a reboot? I don't have a Windows 7 anymore to test on. That could fix any memory problems related to having too many other programs running.
Do you have the latest version of Windows Essentials?
For the free disk space, please go to file explorer and right click -> properties your C: drive. How much free space do you have?
For your office documents, Open Office is free and has worked great for me for years -
Download Apache OpenOffice
If you're not using it already,
Secunia PSI can help get programs updated. Check Windows Add/Remove programs to remove applications you don't use anymore.