I am sure I have a virus. The symptoms are many: screen jumps when browsing and cursor jumps when composing an email, and the system is slow. I tried your recommendation to download Malwarebytes Antimalware. I ran the full scan, and nothing was detected. I heard that using more than one security app can cause problems. Should I delete Microsoft Security Essentials?Malwarebytes Antimalware is not an active antivirus. It runs only when you run it, so no need to uninstall Security Essentials. Your issues don't seem to be symptomatic of a virus. The screen jumps could indicate inadvertent touchpad contact or mouse issues (batteries/dust). Your system slowdown is most likely due to a bloatware creep into your Windows startup, meaning there is an accumulation of programs that start themselves unnecessarily at startup. Some or most of these programs you can probably do without. First, make sure your PC is properly ventilated and that there is no dust accumulation in the fan intake. An overheated CPU slows itself down to prevent damage. This is often overlooked. Next, examine which programs are starting at startup. You didn't mention which version of Windows you use, so I'll just mention the generic Microsoft System Configurator. Click "Start," "Run" and then type "msconfig.exe" and click "OK." Check the Startup tab for a list of programs that run at startup. You will need to check what each process is (use Google) and determine whether it belongs on your system. You can disable a program from starting by unselecting it. If it turns out you do need it, just re-select it.My Gateway 2000 desktop PC is running Windows XP. I usually close down the PC at night and start it up in the morning. This window appears: "Microsoft Visual C++ Runtime Library Runtime Error! Program: C:\Pro. … This application has requested the runtime to terminate it in an unusual way. Please contact the application's team for more info."I close out that and a new window appears: "Update application has encountered a problem and needs to close, sorry for the inconvenience. Debug Close Connecting thru wan miniport (PPPOE) Error 678 Broadband." What's happening?You wrote in your email "Program: C:\Pro. …". I don't know if that was displayed or if you just abbreviated, but that program name is important to finding the cause of the issue. It could be that one of the files related to that program is corrupted or got clobbered by some other installation. If it's happening at start up, click "Start," "Run" and type "MSCONFIG." Click "OK" and then click the "Start-up" tab. See if you can find the program named in the error message and disable it by unchecking the option box. If it's something you need on your system, try uninstalling and then reinstalling it. PPPOE is a type of point-to-point network protocol used in dial-up DSL. Assuming that you do not use DSL for your Internet connection, go to "Control Panel," "Network" and "Internet Connections," click "Set up or change your Internet connection," then the "Connections" tab. Make sure the "Never Dial a Connection" option is checked.Send questions to [email protected] or Personal Tech, P.O. Box 1121, St. Petersburg, FL 33731. Questions are answered only in this column.