Error 1330.A file that is required cannot be installed because the cabinet file cab2.cab has an invalid digital signature.

Error 1330.A file that is required cannot be installed because the cabinet file cab2.cab has an invalid digital signature. This may indicate that the cabinet file is corrupt.

This is a very common error for those who are trying to install Visual Studio 2008 on a Virtual PC using an iso image. I had a tough time with this error, and I spent several hours struggling to solve this issue. I searched internet and most of the forums were asking to keep trying again and again until you are successful. Every time I tried and I got the same error but on a different cab file. Finally, after digging much deeper into the problem, I was able to find the root cause of this issue and solved it. Here we will discuss how to get past this error and install Visual Studio 2008 on a Virtual PC

Let us see what is causing this issue. 


Even though the error message reads that the cab file is corrupt, most probably the underlying reason was that the installer could not read the whole file successfully. Visual studio is a pretty big installation and when you try to install the application on Virtual PC using an ISO image, it uses the Temp directory in the Virtual PC hard disk and the RAM of the Virtual PC to store all the temporary installation files. The reason for this error is momentary unavailability of the hard disk space or RAM. 


In order to fix this error, we need to follow the below steps.


Step - 1: Download the iso image to your host pc and extract the iso image to a folder in the host pc hard drive. The iso image for the trial version can be found here. You can use WinRAR or WinZip to extract the iso image. For this example we will assume that the iso image was extracted to H:\downloads\VisualStudio2008\VS2008ProEdition90dayTrialENUX1435622


Step - 2:Next step is to make sure that enough memory is available to the Virtual PC. Open the Virtual PC console and click “Settings”. You might have to stop the PC, if it is already running.

Select “Memory” and set the RAM size to 1.5 to 2 GB. Click “Ok” and start the Virtual PC

Step - 3:Now we need to increase the virtual memory for the operating system of the Virtual PC. From the start menu of the Virtual PC, right click on “My Computer” and select “Properties”.

Select the “Advanced” tab and click “Settings” in the “Performance” pane.

Select “Custom Paging size” and give values as shown below.

Click OK and restart the Virtual PC


Step - 4:Let us also clear all the files from the temporary folder. In order to do that, from the Start menu of the Virtual PC, select “Run” and type %temp% .This should open up the Temp folder. Delete all the files from this folder.


Step - 5:In the next step , we will copy the extracted iso image from the host pc into the local hard drive of the Virtual PC. This will reduce the number of  file input output operations during the installation. 
In order to copy the file from the host pc, you need to map the folder to which you have extracted the iso image as a Shared folder in the Virtual PC. 


To do that, right click on the small folder icon at the bottom-left corner of the Virtual PC Window and select “Share Folder”

Navigate to the folder to which we have extracted the iso image and click ok.

Now open the file explorer in the Virtual PC, you can see the folder on the host pc as a shared folder. Copy the folder to the Virtual PC C: Drive

Step - 6:Once the copy is complete, open the folder in the C: drive of Virtual PC and double click the setup.exe and follow the installation wizard. The installation will complete without issues. 


Step - 7:In the rare case that a cab file corrupt message comes again, try replacing that particular cab file from host pc. The Visual Studio installation should complete without any issue now.