Can't write to shared folder from a hosted Ubuntu VM

[Zian]

When I try to copy a file from Ubuntu to a shared folder, I get the following message box:

Error while copying "Screenshot from 2012-12-10 14:09:52.png".

There was an error copying the file into /home/zian/Desktop/Shared Folder.

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Error opening file '/home/zian/Desktop/Shared Folder/Screenshot from 2012-12-10 14:09:52.png': Protocol error
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I am running VirtualBox version 4.2.6r82870 on a ThinkPad T400. The T400 runs Windows 7 Ultimate 64-bit edition Service Pack 1. The laptop's virtualization extensions are enabled in the BIOS.

The shared folder is connected to a folder that lives on the laptop's hard drive. The folder is also connected to the virtual machine running Ubuntu Release 12.04 (precise) 32-bit. The guest has the latest version of the VirtualBox additions installed.

Things I've Tried to No Avail:

- Dragging stuff straight to /media/sf_Ubuntu as explained in the VirtualBox user manual
- Restarting the virtual machine
- Reinstalling the guest additions
- Adding my Ubuntu user to the VirtualBox user group
- Installing all the available Ubuntu updates
- Removing and recreating the shared folder
- Looking at the Shared Folders FAQ (viewtopic.php?f=29&t=15868)
- Searching for similar threads online and in particular, in the VirtualBox forums

I still haven't tried recreating the virtual machine. I am hesitant to do so due to the time and effort required.

[mpack]

Post a log file please, preferably as a zipped attachment. The VM log file is called "VBox.log", and can be found in the "Logs" subfolder of your VM folder.

[Zian]

Here it is.

To get this log, I did the following:

1. Started the Ubuntu VM.
2. Dragged and dropped a file into the shared folder.
3. Shut down the VM.

There were many files named "VBoxSVC" so I have selected the one that was modified most recently.

[mpack]

That is not the log I asked for. Please read my previous instructions more carefully.

[Zian]

Sorry about that.

I found a solution though.

Simply upgrade to the latest version of VirtualBox and start a new Ubuntu install using the latest version of the operating system. Then, set up a permanent R/W shared folder with Virtualbox. Then, add your Ubuntu account to the VirtualBox group. Finally, browse to /media and find the shared folder.