windows explorer has encountered a problem and needs to close...

This problem can occur because of many different reason. It can either occur if the Rkadmin.dll file, knowingly or unknowingly, gets copied to the System32 folder. This Rkadmin.dll file will cause some kind of violation while you are accessing a file. but this problem can also occur if your IE is corrupt and requires repair. So i would recommend you to repair your registry entries to solve this problem. Softwares like Perfect optimizer or TuneUp Utilities can help you repair, clean and optimize your registry entries. Search for them on Internet and download from there official website.