Don’t Believe Everything You Read

Recently, I was contacted by a customer who was advised by an ISV to set a registry value under one of the sub keys in HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\.  Let’s call it UseQuantumComputing = 1 (value name has been changed to protect the ISV).  The customer wanted to know what this value actually did and no one…

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How the Clipboard Works, Part 2

Last time, we discussed how applications place data on the clipboard, and how to access that data using the debugger. Today, we’ll take a look at how an application can monitor the clipboard for changes.  Understanding this is important because it is a place where Windows allows 3rd-party code to "hook" into the system.  If you…

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How the Clipboard Works, Part 1

Recently I had the opportunity to debug the clipboard in Windows, and I thought I’d share some of the things I learned.  The clipboard is one of those parts of Windows that many of us use dozens (hundreds?) of times a day and don’t really think about. Before working on this case, I had never even…

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Debugging Backwards: Proving root cause

Matt Burrough here again.  On rare occasions when debugging, we’ll actually know (or strongly suspect) what the root cause of a problem is at the beginning of our analysis – but we still need to investigate to confirm our assertion.  The following is a case study for an issue I worked on recently where the…

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For testing purposes only, and other desktop watermarks

Hi all, Matt here again.  One of our team’s main functions is to work with our development teams to create hotfixes when customers run into issues that can only be resolved through a code change.  The developers will often prepare a private test fix that either tests the proposed change, or adds additional instrumentation to…

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Control Panel Policy and the Missing Icon

A customer recently reported a rather peculiar problem.  They were working on a roll out of Windows 7, and one of the policies they employed on their domain was the “Show only specified control panel applets” setting.  As its name implies, this policy allows an administrator to specify the names of any Control Panel icons…

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Expanding Netmon to aid in debugging

A walk-through of creating a Netmon parser in the context of a real case   As is obvious to frequent readers of our blog, our team logs a lot of time in our debugger of choice (for some windbg, for others kd).  However, a debugger is not always the best tool for the job, and…

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Case Study – Software Restriction Policies and Large EXE Files

Recently I received a debugging request for a customer having problems running large executables. On their systems, they could run most EXEs without any problems, but they had two programs that were over 1.8 GB which, when run, would display the following error: If they tried to run them in a command prompt, they received…

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Unlocking some puzzles requires building a better key… board

Hi, this is Matt from the Windows Performance team.  Sometimes we are presented with problems that defy our usual troubleshooting and require a creative approach.  In a recent case, we needed a way to test the responsiveness of an application as text was typed into its fields.  Initially, we tested the program using a script…

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