Bitcoin Core MinGW Runtime Assertion Error on Wallet Launch

[Gremwatch]

So just today when I tried to launch my bitcoin wallet I am receiving this error I ran a couple searches on the forum and on google but didn't turn up anything. Dose any one who is more familiar with bitcoin wallet have any ideas?

So far i have uninstalled and reinstalled the wallet in both x64 and x86 varieties.

Here is a link to a picture of the error.

https://dl.dropboxusercontent.com/u/87553217/Bitcoin%20Error.PNG

[achow101]

Try starting Bitcoin Core with the -reindex option. If that doesn't work, go to the data directory and delete the chainstate and databases folders.

[Gremwatch]

Cool thanks man that fixed it.

[walsc]

Where ist the data directory?

Edit: OK, found it.