Alphabet.pl is a trojan which has the capability to replace a legitimate file or program so that it goes rogue. Such files if deleted will not solve the problem because the Alphabet spyware will continue to operate from a different source and the infection will continue. Only when it is removed from the source folder, you will be able to restore your computer to its original self. Similar to other virus and trojans, this will reduce PC performance and can even block user from accessing select folders. The best way to stop this file is to remove every file created by the trojan and make sure it doesn't continue to infect others by isolating them. Registry entries are commonly created by most malware. Alphabet.pl trojan is no different and when it does, users have to manually remove all those entries as they are prone to cause issues in the future. Protect browser settings with a password and scan them if required. Update them to latest versions so that any bugs are automatically fixed. Let a AV program and an anti spyware program completely scan your PC to find any instances of Alphabet.pl before you can confirm it is obliterated. It's threat rating level is unknown.