When you tried to delete a personal site collection of a user and you got this error, <nativehr>0x80070003</nativehr> is because the DataBase was corrupted and the site collection is wrong.
You can try with several commands and also using the central administration, you will get the same result, a HRESULT error.
I researched a bit on Internet about this error and I didn't found a solution for it, I have found some posts talking about the similiar errors. In one of them, I found a comment where somebody said that to solve the problem is need detach the database and attach it, here the post http://social.technet.microsoft.com/forums/en-US/sharepointadminprevious/thread/5a3851f1-458e-4e35-b5a3-658eafe81239
The first step is detach and attach the content database from the web application of my sites. The site collecion that was wrong is gone and the other site collections in this database still working very well.
Now is needed recreate the site collection of the user, for this I used the following command in PowerShell.
$UrlsiteColMySite = "https://UrlMySite/"
$siteColMySite = New-Object Microsoft.SharePoint.SPSite($UrlsiteColMySite)
$spContext = [Microsoft.Office.Server.ServerContext]::GetContext($siteColMySite)
$UserProfileService = New-Object Microsoft.Office.Server.UserProfiles.UserProfileManager($spContext)
$userAccount = "domain\user"
$profileUser = $UserProfileService.GetUserProfile($userAccount)
Now you can access again on the profile of the user and navegate to the tab content of the user, you can see the new site collection created.