Wininet API caches on Windows 8

I am using P / Invoke with C # to clear cache entries as follows. The code seems to work perfectly up to Windows 7 on 32 and 64 bit. On Microsoft Windows 8 Release Candidate, it hangs on a call DeleteUrlsFromGroup.

[DllImport(@"wininet",
    SetLastError = true,
    CharSet = CharSet.Auto,
    EntryPoint = "FindFirstUrlCacheGroup",
    CallingConvention = CallingConvention.StdCall)]
private static extern IntPtr FindFirstUrlCacheGroup(
    int dwFlags,
    int dwFilter,
    IntPtr lpSearchCondition,
    int dwSearchCondition,
    ref long lpGroupId,
    IntPtr lpReserved);
// For PInvoke: Retrieves the next cache group in a cache group enumeration
[DllImport(@"wininet",
    SetLastError = true,
    CharSet = CharSet.Auto,
    EntryPoint = "FindNextUrlCacheGroup",
    CallingConvention = CallingConvention.StdCall)]
private static extern bool FindNextUrlCacheGroup(
    IntPtr hFind,
    ref long lpGroupId,
    IntPtr lpReserved);
// For PInvoke: Releases the specified GROUPID and any associated state in the cache index file
[DllImport(@"wininet",
    SetLastError = true,
    CharSet = CharSet.Auto,
    EntryPoint = "DeleteUrlCacheGroup",
    CallingConvention = CallingConvention.StdCall)]
private static extern bool DeleteUrlCacheGroup(
    long GroupId,
    int dwFlags,
    IntPtr lpReserved);
// For PInvoke: Begins the enumeration of the Internet cache
[DllImport(@"wininet",
    SetLastError = true,
    CharSet = CharSet.Auto,
    EntryPoint = "FindFirstUrlCacheEntryA",
    CallingConvention = CallingConvention.StdCall)]
private static extern IntPtr FindFirstUrlCacheEntry(
    [MarshalAs(UnmanagedType.LPTStr)] string lpszUrlSearchPattern,
    IntPtr lpFirstCacheEntryInfo,
    ref int lpdwFirstCacheEntryInfoBufferSize);
// For PInvoke: Retrieves the next entry in the Internet cache
[DllImport(@"wininet",
    SetLastError = true,
    CharSet = CharSet.Auto,
    EntryPoint = "FindNextUrlCacheEntryA",
    CallingConvention = CallingConvention.StdCall)]
private static extern bool FindNextUrlCacheEntry(
    IntPtr hFind,
    IntPtr lpNextCacheEntryInfo,
    ref int lpdwNextCacheEntryInfoBufferSize);
// For PInvoke: Removes the file that is associated with the source name from the cache, if the file exists
[DllImport(@"wininet",
    SetLastError = true,
    CharSet = CharSet.Auto,
    EntryPoint = "DeleteUrlCacheEntryA",
    CallingConvention = CallingConvention.StdCall)]
static extern bool DeleteUrlCacheEntry(string lpszUrlName);

/// <summary>
/// Clears the cache of the web browser
/// </summary>
[HandleProcessCorruptedStateExceptions]
public static void ClearCache(Uri hostName)
{
    if (hostName == null)
    {
        return;
    }

    long groupId = 0;
    try
    {
        // Delete the groups first.
        IntPtr enumHandle = FindFirstUrlCacheGroup(0, CACHEGROUP_SEARCH_ALL, IntPtr.Zero, 0, ref groupId, IntPtr.Zero);
        if (enumHandle != IntPtr.Zero && ERROR_NO_MORE_ITEMS == Marshal.GetLastWin32Error())
        {
            return;
        }

        // Loop through Cache Group, and then delete entries.
        while (true)
        {
            if (ERROR_NO_MORE_ITEMS == Marshal.GetLastWin32Error() || ERROR_FILE_NOT_FOUND == Marshal.GetLastWin32Error())
            {
                break;
            }

            // Delete a particular Cache Group.
            // Hangs on WIndows 8
            bool returnValue = DeleteUrlCacheGroup(groupId, CACHEGROUP_FLAG_FLUSHURL_ONDELETE, IntPtr.Zero);
            if (!returnValue && ERROR_FILE_NOT_FOUND == Marshal.GetLastWin32Error())
            {
                returnValue = FindNextUrlCacheGroup(enumHandle, ref groupId, IntPtr.Zero);
            }
            if (!returnValue && (ERROR_NO_MORE_ITEMS == Marshal.GetLastWin32Error() || ERROR_FILE_NOT_FOUND == Marshal.GetLastWin32Error()))
                break;
        }
        DeleteUrlsFromGroup(hostName); // this hangs on Windows 8
    }
    catch (AccessViolationException)
    {

    }
}

Any ideas / links to changes in the Win API for Windows 8?

Thanks in advance.