Use Window's "Search Advanced Query Syntax", which basically lets you do stuff that Vista and XP advanced search used to let you (that Windows 7 hid). Read about it on MSDN.
Hence, you can just search filename:.
to find all files with a file name that begins with "."
Evaluate Microsoft Desktop Optimization Pack 2011 R2 (x86 and x64) - (English)
Diagnostic and Recovery Toolset
DaRT 5.0 - Windows XP; DaRT 6.5 - Vista; DaRT 7.0 - Windows 7;
Locksmith - reset password tool
x86 - only x86 system!
x64 - only x64 system!
DaRT language = System Language
Need system instalation CD!
Microsoft Desktop Optimization Pack 2011 R2

Select Windows 7 x64 Diagnostic and Recovery

Run Windows 7 x64 Diagnostic and Recovery setup

Open Windows 7 x64 Recovery image wizard

Run Windows 7 x64 Recovery image wizard

Select Windows 7 x64 installation CD

Disable Crash Analyzer
If need Crash Analyzer previously install Windows Driver Kit Version, Debugging Tools for Windows and Windows Symbol Packages.
See: Download and Install Debugging Tools for Windows
MDOP – DaRT Crash Analysis Tools
Additional:
Microsoft Visual Studio 2012 Documentation
Download & Package MSDN & TechNet Content
Windows Hardware Certification Kit Downloads
Driver Development Tools
Stop BSOD IRQL_LESS_OR_EQUAL
HKLM\SYSTEM\CurrentControlSet\Control\SessionManager\MemoryManagement
DisablePagingExecutive DWORD 1

Set DaRT ISO name

Create DaRT boot image

Burn DaRT dialog

Boot from DaRT boot image

Network init

select locale

wait search Windows system

select Diagnostic and Recovery Toolset

select Locksmith tool

Locksmith wizard dialog

select user

Reset user password

Finish Locksmith wizard, or reset other users passwords and restart.

Boot Windows 7 x64
Set new password message

Set new password dialog

apply new password

change password information message

The end!

Best Answer
You could also try using WinDirStat. It'll show all your files as colored rectangles. Bigger rectangles will show bigger files. On the right, you'll have a list of extensions. This way you'll be able to select all files of certain type by clicking on their extension on the right and graphically see their size.