Hi,
What is probably happening is that the workspace meta data is not setup correctly on the new system (probably path related stuff).
What you can try is to update the workspace meta data by 'importing' the solutions. I put those between quotes because you only update this meta data.
Go to the menubar > file > Import. This will open a dialog, select 'Existing Projects into Workspace' under the General node.
- import 1.png (51.72 KiB) Viewed 6270 times
This will open another dialog where under 'Select root directory' you point it to your existing workspace. This should show all the projects in the projects list.
Now make sure the 'Copy projects into workspace' is not checked as you only want to update the meta data.
- import 2.png (65.72 KiB) Viewed 6270 times
Hit the Finish button and your solutions should show up in the Solution Explorer.
Hope this helps.