电脑开机要黑屏好长一段时间

这几天电脑不对劲，开机出现WIN7图标后就黑屏
好长一段时间才进入欢迎界面
愣是没弄明白怎么回事。系统盘SSD。
系统启动日记如下：
+ System
-Provider[ Name]Microsoft-Windows-Diagnostics-Performance[ Guid]{CFC18EC0-96B1-4EBA-961B-622CAEE05B0A}
EventID100
Version2
Level3
Task4002
Opcode34
Keywords0x8000000000010000
-TimeCreated[ SystemTime]2015-07-22T14:38:32.605523600Z
EventRecordID3441
-Correlation[ ActivityID]{054B4C50-F800-0002-679F-D6D98BC4D001}
-Execution[ ProcessID]1796[ ThreadID]884
ChannelMicrosoft-Windows-Diagnostics-Performance/Operational
ComputerXZG-PC
-Security[ UserID]S-1-5-19
- EventData
BootTsVersion 2
BootStartTime 2015-07-22T14:36:52.796400500Z
BootEndTime 2015-07-22T14:38:32.090722600Z
SystemBootInstance 1652
UserBootInstance 1648
BootTime 26343
MainPathBootTime 7743
BootKernelInitTime 30
BootDriverInitTime 306
BootDevicesInitTime 597
BootPrefetchInitTime 0
BootPrefetchBytes 0
BootAutoChkTime 0
BootSmssInitTime 3661
BootCriticalServicesInitTime 884
BootUserProfileProcessingTime 197
BootMachineProfileProcessingTime 525
BootExplorerInitTime 1499
BootNumStartupApps 10
BootPostBootTime 18600
BootIsRebootAfterInstall false
BootRootCauseStepImprovementBits 0
BootRootCauseGradualImprovementBits 0
BootRootCauseStepDegradationBits 0
BootRootCauseGradualDegradationBits 0
BootIsDegradation false
BootIsStepDegradation false
BootIsGradualDegradation false
BootImprovementDelta 0
BootDegradationDelta 0
BootIsRootCauseIdentified false
OSLoaderDuration 2101
BootPNPInitStartTimeMS 30
BootPNPInitDuration 619
OtherKernelInitDuration 167
SystemPNPInitStartTimeMS 781
SystemPNPInitDuration 284
SessionInitStartTimeMS 1071
Session0InitDuration 1996
Session1InitDuration 197
SessionInitOtherDuration 1467
WinLogonStartTimeMS 4732
OtherLogonInitActivityDuration 789
UserLogonWaitDuration 209