Excel and the Mysterious Hang

Sometimes, it’s hard just to figure out which needle you’re looking for in haystack. Once you got it figured out though, that needle will look like a big stick.

My wife came home tonight asking me to look at her laptop. In the last week, her Excel program would hang trying to open Hyperion but would eventually find its way back home. She might have mentioned that Outlook was also opening slowly but having mistook the rest of her sentence as something related to finance, I promptly ignored it – my eyes fixed on the real prize: a chance to tinker.

When you don’t know where the problem is, sometimes it’s best to get all the information and start sifting it for signals. When I started off, I was SURE it was some kind of timeout problem so I immediately started with a packet trace.¹ #NOPE There was nothing evident of a long or delayed response.

Well, I knew Excel was problematic (you know, since I forgot about Outlook) and decided to hone in on the processes involved with it. I fired up the handy little Sysinternals Process Monitor and had my wife run through her steps again. I captured the specimen and moved it into the laboratory for closer examination.

What I was looking for now was a gap. I knew there was some kind of delay or timeout and was hoping something in the procmon trace would show me. If you don’t use any filters to limit the information, no amount of hope is going to make it show up. I had to keep excluding things which was only marginally helpful. I gave up and went all in. I excluded anything that wasn’t Excel and hid all SUCCESS results.

By slowly dragging the net across the screen, I finally managed to see the little tear I was looking for. The time values jumped. That’s significant. It went from 6:42:48 to 6:43:27. It was nearly 40 seconds. That was when I knew what needle I was looking for and when that needle became a big stick.

The events immediately before and after showed reg key calls related to wpad. Hmm. Wpad. That’s familiar. In fact, it probably stands for Windows Proxy Auto Detect. #NOPE #2  According to Wikipedia, it actually stands for Web Proxy Autodiscovery Protocol.

The Web Proxy Auto-Discovery Protocol (WPAD) is a method used by clients to locate the URL of a configuration file using DHCP and/or DNS discovery methods. Once detection and download of the configuration file is complete, it can be executed to determine the proxy for a specified URL.

If that’s really the problem coming out of Excel, I was willing to bet that Excel was using the proxy settings of Internet Explorer. I fired up IE. It hung. HELLZ YEAH. Looking at the LAN settings¹ revealed all. While my wife was onsite at a different company, the local IT staff reconfigured her browser to use their proxy.

I unchecked the Use automatic configuration script setting. IE worked. Excel worked… and uhhh, yeah. So did Outlook. ;-)

Hope that helps you out! Happy hunting.

 

¹ Did you know you can capture packets from a cmd prompt without Netmon, Message Analyzer, or Wireshark installed? Oh, yes, you can. http://marcusoh.blogspot.com/2014/10/using-netsh-to-capture-packets.html

² You can view the LAN settings by navigating to the following path: Internet Explorer / Internet Options / Connections tab / LAN settings.