When you merge two partitions using Partition Magic you have to create a folder where you have the option to copy all the contents of the partition to be merged. After the partitions have been merged you cannot access that folder or do anything with it.
The reason behind this is Partition Magic reassigns permissions on that folder.
To solve it do the following:-
1. Goto "Start->Settings->Control Panel->Folder Options"
2. Goto View Tab
3. Put a check on "Show hidden files and folders"
4. Uncheck "Use simple file sharing (Recommended)"
5. Right click on the folder that you which to access and select "Properties"
6. Goto Security Tab
7. Click on your user type and select "Full Control" under "Permissions"
8. Click Apply & OK
Now you will be able to access the folder and do whatever you want with it.