Expert computing advice (Part 1) - Autorun worm, Sketching software & Two networks, one router

4/4/2012 5:37:56 PM
Expert computing advice (Part 1)

Invalid com errors

My 18-month-old Windows 7 laptop grinds to a halt every time I try to use it. Finding and fixing any registry errors and hard-drive corruption using lob system mechanic solves the problem until the next restart. I’ve uninstalled the progRAMs I don’t use and clear the cache twice a day. I don’t know what to do next. Many of the faults reported by lolo concern invalid COM references (see screenshot, right).

It’s difficult to diagnose this issue without further information, but the fact that a clean-up utility is able to alleviate the problem suggests that it isn’t the laptop’s hardware at fault. If the issue is recurring regularly, it’s possible that you’re running low on hard-drive space.

The Windows registry contains hundreds of thousands of entries, which makes the 20 or so errors reported by system mechanic a drop in the ocean and somewhat irrelevant. Check your remaining disk space next time the problem occurs. You’ve already uninstalled the applications you don’t need, but some additional spring cleaning may be required to tree up enough space for Windows to store the temporary files it creates during normal operation. Keep at least 15 percent of your drive’s capacity free.

Autorun worm

Description: Autorun worm

For several years I’ve been using a portable hard drive to store valuable data, but I recently picked up what I believe to be a malware infection. Microsoft word documents now feature the file extension .exe rather than .doc, while other tiles and directories have been converted to link files. Please help me reclaim my tiles.

This looks like the work of an autorun worm. Such malware is designed to infect shared files on a network, or those stored on removable devices such as your USB drive.

An up-to-date antivirus should be able to detect and remove this worm. Launch your security progRAM, install any updates, then set it to perform a full system scan.

Autorun worms use Microsoft word files as a vehicle on which to propagate themselves, rather than destroying the information stored within. By changing the file extension to .exe, innocent users wanting to open the word document are tricked into launching the malicious code attached.

Because the worm doesn’t tamper with the data stored within the word document. Your antivirus software should be able to clean the infected files and return them to their original state for editing.

McAfee’s ant virus has reportedly recovered tiles damaged in this way; many other progRAMs will also be up to the job.

Sketching software

I’m struggling to find some interior design software for cafés and restaurants for use on my Windows 7 PC. Are you able to recommend some user-friendly software?

Google SketchUp ( is a free application that’s useful for all sorts of 3D design. It’s very powerful, but designed with ease of use in mind; plenty of online tutorials can help you get started.

If you need more functionality, upgrade to SketchUp Pro. This adds professional features and a 2D layout module.

For more simple tasks, such as creating quick floor plans. You can try a site such as This runs within your browser; so you don’t need to download and install additional software. As with Google Sketchup, the basic version is free. More advanced options can be added on a sliding price scale.

Two networks, one router

Description: Two networks, one router

I live above my small business and use six Windows 7 and XP PCs for work and leisure. These are currently linked to a single router and Wi-Fi network. I’d like to separate my home and business networks. But control both from a master PC running Windows 7. Please tell me how to proceed.

There are a number of ways you could achieve this, Ian. The most elegant solution would be to use a router that supports virtual LANs (VLANs). This feature allows a single router to maintain a number of separate networks internally and assign them to different external ports.

Using such a router, you can set up two networks as if you were using two routers. The PCs connected to one network won’t be able to see those configured to access the other. You can also set u wireless clients to attach to the VLANs.

Because the VLANs are managed by the same router, your master PC will see and can be assigned to both simultaneously.

Another approach is to install a second network adaptor in your master PC (some models have two network ports as standard, in which case this isn’t necessary). This solution is more complicated, however, as you would then need to configure each network as a different subnet and set up routing within Windows on the master PC. And if you’re using a DHCP server to assign IP addresses, you would need to ensure that this also has access to both subnets.

If your current wireless router doesn’t support VLANs, you may need to invest in a new model. Take a look at Cisco’s $190.4 RV120W (pictured below) and Netgear’s $302.4 ProSecure UTM5.

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