AbleCommerce Shopping Cart Software

I'm getting this message sometimes when clicking "reccalculate" in shopping cart:

The hoster responded with this:

There are several ways to get around this problem:

1) Host your site on a server that never restarts or recycles!!! Obviously, this is impossible!

2) Disable ViewstateMac by putting this “enableViewStateMac="false"” in your web.config. This approach is not 100% secure.

3) Configure ASP.NET to not use Auto-Generated Key but rather a predefined key. This is the preferred method.

Should I used option 2 or 3? thanks

Use #3 according to an earlier Able post from Logan.

Go to this link: http://aspnetresources.com/tools/keycreator.aspx

Leave the defaults in place, validation key length 64, encryption key length 24, type sha1. Click Generate to create a random machine key for you and copy the result.

Now open the web.config file from your site. Find around line 33 where it shows:

<system.web>

And paste in the <machineKey ... /> on the next line. Save that file.

Thanks Judy,
Here's how it looks for anyone else who needs to do it:

<system.web>
<machineKey validationKey="6DF5E433D8C9405FB87840F9 ..........
decryptionKey="9BACA138B26E39975F31CE4132180179B874 ............
<customErrors mode="Off"/>
<pages theme="AbleCommerce" ....................