1. ⏱ Memory Test

You can read the full tutorial here or receive live tech support if needed.

The error is caused because your computer doesn?t have enough storage capacity (RAM / HDD) to hold the installation files in memory.

The standard error message cited with isdone.dll is:

unarc.dll returned an error code -1ERROR: archive data corrupted (decompression fails)

If you want to do it properly ?

It?s often the case that a faulty module of RAM will be causing the error.

The best way to determine if this is the case is to use either theWindows Memory Diagnostic tool, or a commercial tool called MemTest86:

2. ? RAM Capacity

If the memory test(s) come back okay, you will need to ensure the capacity of your RAM is not being superseded. This can be done with Task Manager:

If the memory usage is anywhere near 100% (for example 85%), you?ll need to stop any running applications:

This can either be done by stopping their ?processes? in Task Manager, or by restarting in ?Safe Mode? (both explained in #3) ?

3. ? Stop Processes (Restart Into Safe Mode)

If you find your memory to be okay, you will need to stop any of the running processes. This will ensure that as much RAM is made available as possible.

The most efficient way to do this is to restart into Safe Mode. Safe Modeloads up Windows without any extra applications, drivers or services ? allowing you to perform any maintenance required. In our case, we will useit to free up the RAM on your system:


The first steps is to restart into ?Safe Mode?:

  • In Windows 7, press ?Start? ? ?Restart?
  • Once you?ve restarted, press F8 continually on your keyboard before Windows starts to load
  • From here, use the F-keys to select the ?Safe Mode? option (typically F4):

4. ? Manually Change RAM (Advanced ONLY)

Whilst seeing the error is bad enough for installation, playing the game is another kettle of fish entirely.

If this is the case, you *may* wish to replace your RAM manually. This is, of course, an advanced strategy only recommended to users who have experience and understand the risks involved (you need to ensure you do not break any of the RAM):

5. ? Use a ?Swap File? (Page File in Windows)

Lastly, probably the best way around this error is to use a swap file.

Swap files provide virtual memory to x86/x64 powered systems, allowing you to ?add? RAM to your system whilst using the same amount of physical RAM capacity. It?s not really recommended, but should work nonetheless:

  • Press ?Windows? + ?R? keys on the keyboard
  • Type ?sysdm.cpl? and press ?OK?:
  • Click on the ?Advanced? tab, and then on the first ?Settings? button:
  • This will load up the ?Virtual Memory? section, from which you should select ?Advanced? and then ?Change? (for the Page File):

This will set a new ?page file? size (which will be used in the case your RAM capacity is maxed out).


As a further note, the majority of people who read this type of information online will just tell you to ?replace isdone.dll?. This is incorrect.

This particular error has nothing to do with isdone.dll, unarc.dll or any other DLL. It is simply the case that your system does not have enough RAM to continue reading the CAB file required to install your game.

?? Further Support ??

If you need further support, there are a number of options?

? Tech support ?

If you need help with any information pertaining to this error, you can use the free live tech support facility on PCFixes.com. It is open 24/7 and totally free:

This will give you the ability to check how many system resources are being used, and whether your system is running too many applications.

? Thanks For Reading! ?

If you need further help, please feel free to ask below?