This behavior can occur if you have faulty computer hardware or a damaged driver or program, or if your Windows core files are damaged.
First determine whether it is caused by software or hardware. Is this an internal Modem? If so try switching slots. Try and locate a different driver. Will windows provide a driver from its driver database? Find someway to eliminate the modem as the problem. What OS are you running?
Also Click Start, point to Programs, point to Accessories, point to System Tools, and then click System Information. On the Tools menu, click System Configuration Utility. On the General tab, click Selective Startup, and then click to clear the following check boxes:
Process Config.sys File
Process Autoexec.bat File
Process Winstart.bat File (if available)
Process System.ini File
Process Win.ini File
Load Startup Group Items
Click OK, and then restart your computer typically when you are prompted. After you restart and test your computer.