It appears that there may be corrupt preference files.  If there is more than one user account on the computer, it is suggested to remove the files for each user account. 

Since there are hidden files you will need to follow the instructions in Section A, then proceed to instructions in Section B below.

Section A

Windows 10 - Instructions to reach hidden files.

1) Access the Control Panel
2) Type "folder" into the search bar and select "File Explorer Options"
3) Then, click on the View tab at the top of the window
4) Under Advanced Settings, locate "Hidden files and folders..."
5) Then, click on "Show hidden files, folders, and drives"
5) Click on OK
6) Hidden files will now be shown when performing searches in Windows Explorer

Windows 8 - Instructions to reach hidden files.

1)  Access the Control Panel
2)  Type "folder" into the search bar and select Show hidden files and folders
3)  Then, click on the View tab at the top of the window
4)  Under Advanced Settings, locate "Hidden files and folders..."
5)  Click on OK
6)  Hidden files will now be shown when performing searches in Windows Explorer

Windows 7 - Instructions to reach hidden files.

1)  Open Folder Options by clicking the Start button, Clicking Control Panel, clicking Appearance and Personalization, and then clicking Folder Options.
2)  Click the View tab
3)  Under Advanced Settings, click Show hidden files and folders, and then click OK

Section B

Windows 7, 8, & 10

1)  Go to: C:\ProgramData\Cisco\CiscoAnyConnect Secure Mobility Client\Profile or C:\ProgramData\Cisco\Cisco Secure Client\VPN\Profile
2)  Delete all the files in this folder
3)  Go to: C:\Users\%username%\AppData\Local\Cisco\Cisco AnyConnect Secure Mobility Client or C:\Users\%username%\AppData\Local\Cisco\Cisco Secure Client\VPN
4)  Delete preferences.xml
5)  Right click the Cisco icon in system tray and quit Cisco AnyConnect (or Cisco Secure Client)
6)  Launch the VPN after deleting everything, put vpn.illinois.edu in the server window and use your NetID and password to log in via the "Split Tunnel" profile. If you are planning to use Library resources you might need to use "tunnel all".