Malware (for "malicious software") is any program that is harmful to a computer user. Thus, malware includes viruses, worms, Trojans, adware, spyware, keyloggers, rootkits, etc.
Short for Host Intrusion Prevention System, provides rule and behavior-based system monitoring to guard against unwanted changes. HIPS can be used alongside traditional antivirus software to add an extra layer of security.
Why Malware Defender failed to download kernel symbols?
There are two possible reasons. First, Malware Defender cannot connect to the Microsoft public symbol server due to network problems. The second reason is that the corresponding kernel symbols does not exist on the server. For example, there is no kernel symbols for beta version of Windows.
If the kernel symbols are not available, some Anti-Rootkit functions will not work, but all HIPS functions will work fine.