Virus:Win32/Patchload.A is a detection for files, typically DLL files, that are infected by a virus. When an infected file is executed it attempts to execute or load other files, which are often malicious.
In the wild, Windows system files such as <system folder>\dsound.dll and <system folder>\ddraw.dll have been infected and are then detected as Virus:Win32/Patchload.A.
Note - <system folder> refers to a variable location that is determined by the malware by querying the Operating System. The default installation location for the System folder for Windows 2000 and NT is C:\Winnt\System32; and for XP, Vista, and 7 is C:\Windows\System32.
Some of the file names it attempts to execute or load are:
Analysis by Francis Allan Tan Seng
There are no common symptoms associated with this threat. Alert notifications from installed antivirus software may be the only symptom(s).